# Openers, Crackers & Crushers

Ask what is being opened first: cans, jars and nuts need completely different tools. For cans, where the wheel cuts decides sharp edges, hygiene and how hard the tool is to learn. Sore hands need a lock-on or motorised tool, not a brand name. Lever crackers usually fail on macadamias; use a screw cracker or a hammer.

## How it works

A can is sealed by a double seam: lid edge and can wall folded and pressed tight, with glue inside. A rotary opener pinches that rim between a toothed feed wheel and a cutting wheel, walked round by the key. A classic opener cuts down through the lid inside the rim, so the lid drops in sharp-edged and the wheel touches the food. A safety opener cuts sideways into the seam itself, so the lid lifts off smooth and the wheel stays dry. A vacuum holds a jar lid down; jar openers add grip, leverage, or break that vacuum. A lever nutcracker is fast but can crush the kernel; a ratchet is slow but keeps it whole; a screw reaches a macadamia's weak spot but can crush it too. That shell needs about 2,000 newtons, the weight of roughly 200 kg, more than an ordinary lever cracker usually delivers. [6] [7] [1] [20] [22] [23] [24]

| Family | What it is | Suits |
|---|---|---|
| Classic rotary can opener | Squeeze the arms, turn the key; the wheel cuts down through the top inside the rim. | Anyone who wants the fastest, most familiar tool and does not mind sharp lids. |
| Safety (smooth-edge) can opener | Sits on the can and cuts sideways into the rim, so lid and can are left without sharp edges. | Households that hate fishing out sharp lids or want to put the lid back on. |
| Electric can opener | A countertop motor that spins the can, or a battery unit that crawls round the rim on its own. | People with arthritis or weak grip, and anyone opening many cans. |
| Fixed-blade can opener | A single folding tooth (the P-38 type) or church key walked round the lid by hand. | Hiking trips, where low weight and few parts beat comfort. |
| Jar opener | A rubber grip pad, a lever or strap that clamps the lid, a wedge that breaks the vacuum, or a motor. | Anyone who struggles with tight lids, most of all older adults. |
| Lever nutcracker | Hinged jaws squeezed by hand, sometimes spring-loaded; also used for crab and lobster. | Walnuts, hazelnuts, almonds and pecans, and shellfish at the table. |
| Screw or ratchet nutcracker | A screw or a jack-like ratchet that closes on the nut in small steps. | Whole kernels, Brazil nuts, and the usual home tool for macadamias. |

## How an expert narrows the choice

```mermaid
timeline
  section 1 · What it opens
    cans : ask Where the wheel cuts, Works left-handed, Handles ring-pull cans : skip Hardest nut it cracks, Cracks nuts or decoration, How it cracks, How it opens jars
    jars : ask How it opens jars : skip Where the wheel cuts, Hardest nut it cracks, Handles ring-pull cans, Cutter comes off to clean, Works left-handed, Cracks nuts or decoration, How it cracks, Plug-in or battery
    nuts : ask Hardest nut it cracks, Cracks nuts or decoration : skip Where the wheel cuts, How it opens jars, Handles ring-pull cans, Cutter comes off to clean, Works left-handed, Plug-in or battery
    crab and lobster : skip Where the wheel cuts, Hardest nut it cracks, How it opens jars, Handles ring-pull cans, Cutter comes off to clean, Works left-handed, Plug-in or battery, Cracks nuts or decoration, How it cracks
    crushing ice or cans : skip Where the wheel cuts, Hardest nut it cracks, How it opens jars, Handles ring-pull cans, Cutter comes off to clean, Works left-handed, Plug-in or battery, Cracks nuts or decoration, How it cracks
  section 2 · Hand effort
    motorised : ask Plug-in or battery
    squeeze and turn / turn only : skip Plug-in or battery
  section 3 · Where the wheel cuts
    top cut : ask Cutter comes off to clean
  section 4 · Hardest nut it cracks
    macadamias too : ask How it cracks
```

1. **What it opens.** Cans, jars, nuts, crab and lobster, or crushing (ice/cans)?
   Each answer is a different tool family with its own facets, so one answer removes most of the catalog and decides which later questions exist at all.
   If cans: ask Where the wheel cuts, Works left-handed, Handles ring-pull cans; skip Hardest nut it cracks, Cracks nuts or decoration, How it cracks, How it opens jars.
   If jars: ask How it opens jars; skip Where the wheel cuts, Hardest nut it cracks, Handles ring-pull cans, Cutter comes off to clean, Works left-handed, Cracks nuts or decoration, How it cracks, Plug-in or battery.
   If nuts: ask Hardest nut it cracks, Cracks nuts or decoration; skip Where the wheel cuts, How it opens jars, Handles ring-pull cans, Cutter comes off to clean, Works left-handed, Plug-in or battery.
   If crab and lobster: skip Where the wheel cuts, Hardest nut it cracks, How it opens jars, Handles ring-pull cans, Cutter comes off to clean, Works left-handed, Plug-in or battery, Cracks nuts or decoration, How it cracks.
   If crushing ice or cans: skip Where the wheel cuts, Hardest nut it cracks, How it opens jars, Handles ring-pull cans, Cutter comes off to clean, Works left-handed, Plug-in or battery, Cracks nuts or decoration, How it cracks.
   Skip if already known: product type already named in the query.

2. **Hand effort.** Squeeze and turn, turn only, or motorised?
   Grip and wrist torque decide whether a tool works for this buyer at all, across cans, jars and nuts. Turn only or motorised answers rule out every squeeze-and-turn tool.
   If motorised: ask Plug-in or battery.
   If squeeze and turn or turn only: skip Plug-in or battery.
   Skip if already known: arthritis or limited grip mentioned earlier.

3. **Where the wheel cuts.** Smooth edges you can lift off, or classic top cut?
   Testers split on this for nearly a decade (2015 to 2024); it is preference, not quality, so asking beats guessing. It divides can openers into two families.
   If top cut: ask Cutter comes off to clean.

4. **Hardest nut it cracks.** Walnuts and pecans, or macadamias too?
   Macadamias usually beat ordinary lever crackers, so that answer points to a screw, ratchet or specialist cracker.
   If macadamias too: ask How it cracks.

## What to surface

### What it opens

The thing the tool is made to open, crack or crush. Can openers, jar openers and nutcrackers solve different problems: cutting a folded metal seam, overcoming a vacuum lid, and breaking a shell without crushing the kernel. Nothing an expert says about one family applies to the others, so every later question depends on this one. A tool that only lifts crown caps is not in scope here; see bottle-wine-serving-tools. A multi-tool that adds a cap lifter or ring-pull hook to a can or jar opener keeps that opener's family. [6] [20] [22] [16]

Values: cans, jars, nuts, crab and lobster, crushing ice or cans.
Question to ask: Cans, jars, nuts, crab and lobster, or crushing (ice/cans)?

Used as: top-level split, filter. Data: derived from listing fields, backfill cost none. Look for it as: The product type word is in every brand product name read (Can Opener, Jar Opener, Seafood Cracker, Nutcracker). Retail titles were not fetchable.
Classify from the title's primary product-type word. Classify a multi-tool by whichever job its title leads with; record a secondary function as a note, not a second value, since this facet is single-valued. Crown-cap-only tools are out of scope; their home is bottle-wine-serving-tools.

### Hand effort

What your hands have to do: keep squeezing while you turn, only turn because the tool locks on, or nothing because a motor does it. Classic can openers make you squeeze the arms the whole time; lock-on safety openers, lever jar openers and ratchet nutcrackers do not. Battery motors remove grip entirely, but countertop electric motors still need the lever held down. America's Test Kitchen recommends electric openers for arthritis, though safety openers can need slightly more force to turn. Jar studies put the twist (torque) nearly everyone can manage near 2 newton metres, below what many sealed jars need. [1] [4] [9] [14] [17] [18] [26]

Values: squeeze and turn, turn only, motorised.
Question to ask: Squeeze and turn, turn only, or motorised?

Used as: top-level split, filter. Data: needs research, backfill cost low. Look for it as: Brand descriptions say it in words: locks on, no need for continual squeezing, hands-free, requires batteries, little grip strength.
Classic squeeze-arm can openers without a lock button, and lever nutcrackers, default to squeeze and turn. Lock-button traditional openers and safety (smooth-edge) openers default to turn only. Electric or battery in the title means motorised.

### Hardest nut it cracks

Whether the cracker is made only for everyday nuts such as walnuts, pecans, hazelnuts and almonds, or also for macadamias. A macadamia shell needs about 2,000 newtons to crack, more than an ordinary lever cracker can usually manage, so macadamia owners often need a screw cracker, a specialist cracker, or a hammer. For everyday nuts any working cracker will do and the choice moves to keeping kernels whole. The answer walnuts and pecans maps to everyday nuts. [23] [24] [22] [25]

Values: everyday nuts, macadamias too.
Question to ask: Walnuts and pecans, or macadamias too?

Used as: top-level split, filter. Data: needs research, backfill cost medium. Look for it as: Macadamia crackers name the nut in the title; others list the nuts they suit in the description, if at all.
Default lever crackers to everyday nuts. Mark macadamias too only where the brand names macadamia.

### Where the wheel cuts

Whether the cutting wheel goes down through the lid inside the rim, sideways into the rim itself, or sideways into the wall just below the rim. Top cut is faster and familiar but leaves a sharp lid that sinks into the food, and the wheel gets wet. Rim cut leaves lid and can smooth, the lid can go back on, and the wheel never touches food, but it is harder to learn. Below-rim cut gives a smooth lid but a sharp, floppy can. Rule: smooth edges means rim cut; classic means top cut; below-rim is a separate, weaker result. [1] [3] [4] [9] [11] [13]

Values: top cut, rim cut, below-rim cut.
Question to ask: Smooth edges you can lift off, or classic top cut?

Used as: top-level split, filter. Data: needs research, backfill cost medium. Look for it as: Safety models say smooth edge, safe edge, SmoothTouch or cuts along the side in the name or first lines. Silence usually means top cut.
Top versus side is cheap from brand wording. Rim versus below-rim is rarely stated; 'removes the entire top' signals below-rim. Resolve that split from reviews for the top N only; do not infer rim cut from 'smooth edge' marketing alone.
Chart: Where the wheel cuts.

### Cracks nuts or decoration

Whether a figure nutcracker actually cracks nuts or is an ornament shaped like one. Most soldier-style nutcrackers sold in the United States are ornaments whose jaws cannot crack a nut, and price does not tell you which. National Geographic's search found an expensive boutique soldier no better than a cheap one. A buyer who wants to crack nuts should filter ornaments out. [27] [22]

Question to ask: To crack nuts, or as a decoration?

Used as: filter. Data: needs research, backfill cost low. Look for it as: Decorative listings say Christmas, holiday decor or figurine; working ones say functional or name nuts.
Treat any figure nutcracker as decorative unless the listing says it cracks nuts.

### Works left-handed

Whether a left-handed person can use the can opener without an awkward hand-over-hand grip. Classic can openers are built for the right hand and left-handed versions are rare. Safety openers that sit on top of the can are easier for lefties, as are electric models. Some disc-shaped openers turn either way. [1] [4]

Question to ask: Left-handed?

Used as: filter. Data: needs research, backfill cost medium. Look for it as: Rarely stated; occasionally 'left or right-handed' in a feature line.
Derive a first guess: electric opener is true. Safety and classic openers both default to false; ATK notes lefties on either still turn the handle the 'wrong' way, unless sold as left-handed.

### How it cracks

Whether a nutcracker uses hinged lever jaws, a screw, a jack-like ratchet, or a falling weight. Levers are quick but take effort and break kernels. A ratchet is slow and fiddly but needs little effort and keeps kernels whole, even Brazil nuts. Screws suit macadamias. Weights pulverise. Check the jaw opening too: testers found older crackers' holes too small for today's larger nuts. [26] [22] [27]

Values: lever, screw, ratchet, impact.

Used as: shown on the card, filter. Data: needs research, backfill cost low. Look for it as: Named in titles of screw and ratchet crackers; lever crackers rarely say so. A photo answers it.
Default to lever when the title says nutcracker and nothing else. A close-up photo settles screw versus ratchet versus lever when the title does not say.

### How it opens jars

Whether a jar opener adds grip (a rubber pad), adds leverage (a handle that clamps the lid), breaks the vacuum (a wedge under the lid edge), or uses a motor. A vacuum-sealed lid takes more torque than many people can produce, and a grip pad only adds friction. A clamping lever multiplies the twist; a vacuum breaker removes the reason the lid is tight; a motor removes the twist entirely. One study's authors caution that non-slip material alone, without the right grip and hand, may raise load and pain in arthritic hands, so a grip pad is not automatically the gentle choice. [20] [14] [15] [19] [21] [17] [18]

Values: grip pad, lever or strap, vacuum breaker, electric.

Used as: shown on the card, filter. Data: needs research, backfill cost low. Look for it as: Brand descriptions say adjustable band, locking mechanism, break the vacuum seal, or electric.
Classify from description words; a photo usually settles grip pad versus lever.

### Plug-in or battery

For motorised openers, whether it is a corded countertop machine or a battery unit that sits on the can. Countertop models opened cans faster than battery models in America's Test Kitchen's timing and survived its durability tests; two of its three battery models were wobbly and broke. Battery units fit a drawer and need no outlet, but Bon Appétit also found its battery pick much slower than a manual opener. Light countertop models can tip with a heavy can. [3] [5] [10] [12]

Values: corded countertop, battery on the can.
Question to ask: Plugged in on the counter, or battery on the can?

Used as: shown on the card, filter. Data: needs research, backfill cost low. Look for it as: Titles say electric or automatic; battery units say rechargeable, cordless or requires batteries.
Only applies to can openers. Electric with a cord-storage line means countertop. Motorised jar openers exist but are classified under jar_mechanism's electric value instead, not this facet.

### Handles ring-pull cans

Whether the opener can latch onto and cut a ring-pull can, for when the tab snaps. Ring-pull lids use thicker metal, and many openers cannot latch onto them or jam at the tab. In America's Test Kitchen's electric test most models failed or jammed on them. BBC Good Food tests every opener on one for this reason. It matters most to buyers with weak hands, who struggle with the tabs themselves. [3] [4] [9]


Used as: shown on the card. Data: needs research, backfill cost high. Look for it as: A few brands claim it in a feature line (opens pop-top and regular cans); most say nothing.
Record only brand claims or review results, which today cover only the top N electric openers from one 2021 test. Expect most other products to have unknown coverage; do not infer a fail from silence.

### Cutter comes off to clean

Whether the cutting wheel or cutting lever detaches for washing or replacement. The FDA's 2022 Food Code, a model code food services can adopt, sets the rule that can-opener cutting parts must be removable for cleaning and kept sharp, because dull or pitted cutters shed metal fragments into food and cannot be sanitised. IEC 60335-2-14 is a real consumer safety standard for electric kitchen machines, including can openers, so this hazard statement is the best guide mainly for manual cutters. It matters most on top-cut openers, whose wheel dips into the food. [8] [29] [10] [1]


Used as: shown on the card, filter. Data: needs research, backfill cost low. Look for it as: Electric models name it in the title or features (removable cutting lever); none of the manual brand pages read mentioned it.
Leave manual openers unknown unless stated. Pair with the kitchen-standard dishwasher_safe field rather than duplicating it.

## What you give up

- A rim-cut safety opener gives smooth edges, a lid that goes back on and a wheel that never touches food. You give up the fast, obvious action of a classic opener and accept a learning curve: no hiss, and the can looks unchanged when it is done. [1] [2] Board branch: "See more smooth-edge openers".
- A motor removes squeezing and twisting, which is why testers recommend it for arthritis. In return you get a bulkier tool and a battery model that may open slowly or fail outright (two of three broke in one test), where a good manual opener keeps working. [3] [5] [1] Board branch: "See more manual openers that lock on".
- A ratchet closes in small steps and keeps the kernel whole, even in a Brazil nut, but it is slow and fiddly. A screw reaches a macadamia's weak spot but can crush the kernel rather than cleanly cracking it. A lever cracker is quick and simple but takes more effort and breaks more kernels. [26] [22] Board branch: "See more crackers that keep kernels whole".

## How to draw it

**Where the wheel cuts** (other, shows Where the wheel cuts). A cross-section of the can's folded rim with three marks: down through the lid, into the rim, and into the wall below it. A buyer sees which edges end up sharp and whether the wheel reaches the food. America's Test Kitchen describes these positions in words only. This is a proposal, nobody draws it this way yet. [3] [1] [7]

## Words you will meet

- **Double seam**. The rim of a can, where the lid edge and the top of the can wall are folded together and pressed tight.
- **Feed wheel**. The small toothed wheel that grips the can rim and drives it past the cutting wheel.
- **Safety can opener**. A can opener that cuts sideways into the rim rather than down through the lid, so no edge is left sharp; also sold as smooth-edge.
- **Top cut**. The classic cut, made down through the lid just inside the rim.
- **Ring-pull can**. A can with a tab you lift to peel the lid off, also called a pull-top or pop-top can.
- **P-38**. A tiny folding military can opener with one hinged tooth that you walk round the lid by hand.
- **Church key**. A flat metal opener with a pointed end for piercing cans and a hooked end for lifting bottle caps.
- **Vacuum seal**. The low pressure inside a sealed jar, which pulls the lid down and makes it hard to turn.
- **Torque**. Twisting force, measured in newton metres (N m); the twist a jar lid needs before it moves.
- **Newton**. The unit of force; roughly the weight of a small apple held in the hand.
- **Micropyle**. The small white dot on a macadamia shell, where the shell is thinnest and cracks most easily.
- **Ratchet nutcracker**. A cracker that closes on the nut a notch at a time, like a car jack.
- **Crab cracker**. A lever cracker with textured jaws for crab and lobster shells, built like a nutcracker.

## Where we made a call

- No can opener suits everyone; cut style is a preference to ask about, not a quality ranking. (confidence high). America's Test Kitchen changed its winner between safety and classic models across nearly a decade of tests (2015 to 2024) and now names one of each. BBC Good Food calls it a matter of preference. [2] [1] [4]
- Among smooth-edge openers, cutting into the rim beats cutting below it, which leaves a sharp, floppy can. (confidence medium). Sources disagree. America's Test Kitchen penalised below-rim cutters in both its manual and electric tests. BBC Good Food praises openers that cut just under the rim. We side with ATK because it inspected the can walls. [1] [3] [4]
- Buyers with arthritis or weak grip should be shown motorised or lock-on tools first. (confidence high). ATK recommends electric openers for limited grip and notes lock-on safety openers need no squeezing; BBC says electric suits those who struggle. Dianat found many people, especially women and children aged 5 to 9, cannot reach the torque sealed jars need; Voorbij measured what grip people, not lids, can produce. [1] [4] [17] [18]
- Rubber grip pads help with slippery lids but are not proven gentle on arthritic joints. (confidence medium). Sources disagree. Epicurious calls them helpful for arthritis. McGee and Mathiowetz's best-performing condition for grip and success also used nonskid material, but they caution it alone, without the right technique, may raise load and pain. We do not rank pads as the gentle option. [21] [19]
- Ordinary lever nutcrackers usually fail on macadamias; a screw, specialist cracker, or hammer works instead. (confidence medium). Sources disagree. Two measurements agree on about 2,000 newtons (Wikipedia citing Jennings 1986; 2,240 plus or minus 430 N in a 2015 study), more than an ordinary lever cracker is typically built for. The Australian Macadamia Society says a hammer or rock also works. [23] [24] [22] [25]
- Most figure nutcrackers sold today are ornaments that cannot crack nuts; price alone does not tell you which. (confidence high). Wikipedia: 'expensive working designs are still available.' National Geographic's own $188 handmade soldier worked; a $200 decorative one did not. [27] [22]
- IEC 60335-2-14 and UL 982 are real consumer safety standards for electric openers; the FDA Food Code covers manual cutters' hygiene only. (confidence high). IEC 60335-2-14's scope lists 'can openers' among covered kitchen machines; UL 982 names 'can openers' in its scope too. Neither covers manual (non-electric) openers, so the Food Code's hazard statement, metal fragments from dull cutters, is still the best guide for those. [8] [29] [30]
- No ice crusher or can crusher expertise was found, so the register stops at the job value for them. (confidence low). Ours. No reviewer, standard or community source was reached for either. Garlic crushers are left to the mashers sibling.
- The Arthritis Foundation's Ease of Use certification is the one third-party hand-effort test found, and no opener carried it on 2026-10-25. (confidence medium). The program tests products in a lab and with patients and licenses a seal on a pass. The opener result comes from searching the Foundation's certified-products sitemap on the date given. [28]
- Crab and lobster crackers, and jar openers past jar_mechanism, do not narrow further on a second source. (confidence low). Ours. The only jar lid diameter data found (Zyliss, 2 to 10 cm) is one source, so it was dropped rather than made a question. No seafood-cracker split was sourced either. [14] [16]

## References

1. [America's Test Kitchen, The Best Can Openers (2024)](https://www.americastestkitchen.com/equipment_reviews/2020-can-openers) (specialist review). Supports: Classic openers cut down inside the rim; safety openers cut sideways, leaving smooth edges; No part of a safety opener touches the can's contents; Below-rim safety cutters leave sharp can walls and a flexible can; Electric openers recommended for arthritis; lock-on safety openers need no squeezing; Classic openers are awkward for lefties; top-mounted safety openers are easier; Blades dull, parts rust; dry and oil to extend life; Safety openers may expose glue that helps seal the lid to the can; Some users need slightly more force to turn a safety opener's handle; A lock button lets some traditional openers turn without squeezing the arms.
2. [America's Test Kitchen, The Trouble with Can Openers (2023)](https://www.americastestkitchen.com/articles/6895-the-trouble-with-can-openers) (specialist review). Supports: Winners alternated between safety and classic models after reader and test-cook complaints; The perfect can opener does not exist; it depends on priorities.
3. [America's Test Kitchen, The Best Electric Can Openers (2021)](https://www.americastestkitchen.com/equipment_reviews/2323-testing-electric-can-openers) (specialist review). Supports: Models cut at three positions: top, below the rim, into the rim; Countertop models opened cans faster than battery models; Wobbly battery models broke in testing; Most models failed on pull-top cans; oval cans tripped both winners.
4. [BBC Good Food, Best can openers (tested)](https://www.bbcgoodfood.com/review/best-can-openers-test) (specialist review). Supports: Two designs: cut inside the rim on top, or round the side under the rim; Electric openers suit left and right hands and those who struggle with manual ones; Each opener tested on a ring-pull can for snapped tabs.
5. [Bon Appétit, The Best Can Openers (2025)](https://www.bonappetit.com/gallery/best-can-opener) (specialist review). Supports: Battery opener much slower than a manual one; A chef advises manual openers unless mobility is limited; motors can burn out; Many openers are hand-wash only; dishwashers can dull blades and cause rust.
6. [Wikipedia, Can opener](https://en.wikipedia.org/wiki/Can_opener) (primer). Supports: Rotary design pairs a cutting wheel with a serrated feed wheel; Safety openers cut through the outside seam and leave a non-jagged edge; P-38 and church key described.
7. [Wikipedia, Double seam](https://en.wikipedia.org/wiki/Double_seam) (primer). Supports: A double seam mechanically interlocks the lid and can body in five folded layers.
8. [FDA Food Code 2022, sections 4-202.15 and 4-501.11 (Internet Archive copy)](https://web.archive.org/web/2024/https://www.fda.gov/media/164194/download) (regulator). Supports: Can-opener cutting parts must be readily removable for cleaning and replacement; Cutting parts must be kept sharp to minimise metal fragments in food; Pitted or uncleanable can openers must be replaced.
9. [Hamilton Beach SmoothTouch Can Opener 76606FG](https://hamiltonbeach.com/smoothtouch-can-opener-76606fg) (spec sheet). Supports: Side cut gives a smooth lid and minimises blade contact with food; Claims to open pop-top and regular cans; Lever operation requires little grip strength.
10. [Hamilton Beach Extra-Tall Can Opener with Removable Cutting Lever 76700G](https://hamiltonbeach.com/extra-tall-can-opener-with-removable-cutting-lever-stainless-steel-76700g) (spec sheet). Supports: Removable cutting lever named in the product title for rinsing clean; Countertop corded model with cord storage.
11. [Zyliss Safe Edge Can Opener](https://www.zyliss.com/products/zyliss-safe-edge-can-opener) (spec sheet). Supports: Brand wording for a safety opener: cuts along the side of the lid, touch-safe edge.
12. [Zyliss EasiCan electronic can opener](https://www.zyliss.com/products/zyliss-easican-electronic-can-opener) (spec sheet). Supports: Battery on-can opener that cuts from the side; requires batteries.
13. [Joseph Joseph GoRound Easy-Open Can Opener](https://us.josephjoseph.com/products/goround-easy-open-can-opener-stone-green) (spec sheet). Supports: Brand wording 'removes the entire top of your can' marks a below-rim cutter.
14. [Zyliss Jar Opener](https://www.zyliss.com/products/jar-opener) (spec sheet). Supports: Description: extra long handle and adjustable band; 'ideal for those with limited hand strength'.
15. [Zyliss 5 Way Opener](https://www.zyliss.com/products/zyliss-5-way-opener-20260) (spec sheet). Supports: Multi-opener designed to break the vacuum seal on jars.
16. [Zyliss Seafood Cracker](https://www.zyliss.com/products/seafood-cracker) (spec sheet). Supports: Serrated stainless jaws for lobster, crab and nuts; dishwasher safe.
17. [Voorbij and Steenbekkers, The twisting force of aged consumers when opening a jar, Applied Ergonomics 2002](https://pubmed.ncbi.nlm.nih.gov/11831209/) (academic). Supports: About 2 N m opening torque would let nearly all older users open jars.
18. [Dianat, Asadi and Castellucci, Mismatch between jar opening demands and wrist torque strength, Applied Ergonomics 2021](https://pubmed.ncbi.nlm.nih.gov/33799123/) (academic). Supports: Vacuum-sealed jars needed more torque than many participants, most of all women and children, could produce; Proposed a 1.8 N m torque limit for jars.
19. [McGee and Mathiowetz, Evaluation of Hand Forces During a Joint-Protection Strategy, AJOT 2017](https://pubmed.ncbi.nlm.nih.gov/28027044/) (academic). Supports: Non-slip material alone may increase load on arthritic joints and pain when opening jars.
20. [Wikipedia, Jar opener](https://en.wikipedia.org/wiki/Jar_opener) (primer). Supports: Types: grooved two-handle openers, rubber rounds, belt loops; lift-off-lid wedges (production halted after 2000); Motorised jar openers exist; Black & Decker made the first.
21. [Epicurious, This Is Your Grandma's Rubber Jar Opener](https://www.epicurious.com/shopping/this-is-your-grandmas-rubber-jar-opener-and-it-should-be-yours-too) (primer). Supports: Rubber grip pads add friction on slippery lids; described as helpful for arthritis.
22. [Wikipedia, Nutcracker](https://en.wikipedia.org/wiki/Nutcracker) (primer). Supports: Designs: levers, screws and ratchets; ratchets avoid damaging the kernel; Screw crackers used for macadamias, too hard for ordinary nutcrackers; Lever crackers also used for crab and lobster; Few decorative US nutcrackers are functional.
23. [Wikipedia, Macadamia](https://en.wikipedia.org/wiki/Macadamia) (primer). Supports: Macadamia shell requires around 2000 N to crack; Ordinary nutcrackers apply insufficient force; specialist crackers target the micropyle.
24. [Pretreatment of Macadamia Nut Shells with Ionic Liquids, ACS Sustainable Chemistry and Engineering 2015 (abstract)](https://api.openalex.org/works/W2321324974) (academic). Supports: Australian macadamia shells required 2240 plus or minus 430 N to crack.
25. [Australian Macadamia Society, How to crack a macadamia nut](https://www.australian-macadamias.org/grow/how-to-crack-a-macadamia-nut/) (other). Supports: Macadamias are the world's hardest nut to crack; target the white micropyle.
26. [The Independent, Tried and tested: seven nutcrackers (1994)](https://www.independent.co.uk/arts-entertainment/tried-tested-taking-a-crack-at-it-we-sample-seven-nutcrackers-the-hard-shell-won-when-it-came-to-the-1392361.html) (specialist review). Supports: Ratchet cracker slow but little effort, best at keeping kernels whole; Traditional lever took effort and broke kernels; holes too small for larger nuts; Weighted impact cracker pulverised nuts.
27. [National Geographic The Plate, Why Fancy Nutcrackers Don't Actually Crack Nuts (2014, Internet Archive copy)](https://web.archive.org/web/20150403083859/http://theplate.nationalgeographic.com/2014/12/08/why-nutcrackers-dont-actually-crack-nuts/) (primer). Supports: Boutique soldier nutcrackers crack no better than cheap ones; Larger modern nuts no longer fit many nutcrackers' mouths.
28. [Arthritis Foundation, Ease of Use Certification](https://www.arthritis.org/partnership/ease-of-use-certification) (standards body). Supports: Lab and patient testing with a pass or fail result; a pass licenses the seal; Sitemap search on 2026-10-25 found 51 ease-of-use-products pages, none an opener.
29. [IEC 60335-2-14 ed. 5.2 (2006+A1:2008+A2:2012), Particular requirements for kitchen machines](https://webstore.iec.ch/publication/1545) (standards body). Supports: Scope and NOTE 101 name 'can openers' among covered household kitchen machines.
30. [UL 982, Standard for Motor-Operated Household Food Preparing Machines](https://www.shopulstandards.com/ProductDetail.aspx?productid=UL982) (standards body). Supports: Scope names can openers among covered household motor-operated kitchen accessories.