# Document Filing & Binders

Ring size is the number every title leads with, but ring shape decides how much a binder holds: by sources, D-rings take about 30 to 50 percent more sheets than round rings of the same size, and pages lie flat. Rings, folders or a display book decide which facets matter; page size and hole pattern must match. Keepsakes need PVC-free.

## How it works

Filing products hold loose sheets in one of three ways. Rings thread through punched holes, so pages stay in order and can be added or removed; this covers ring binders, lever arch files and sheet protectors. Folders and pockets hold sheets loose, so anything fits without punching but pages can shuffle or slip out; this covers file folders, hanging folders, expanding files and wallets. Display books bind a fixed set of clear sleeves, so pages stay protected but the book cannot grow. In ring products, capacity comes from the ring's inner space, not its stated size: a D-ring has a flat side mounted on the back cover, so pages lie flat, while a round ring sits on the spine and the stack curves. Holes must match the rings: North America uses three holes 4.25 in (108 mm) apart, ISO countries two or four holes 80 mm apart. [17] [3] [2] [15] [16] [11] [27]

| Family | What it is | Suits |
|---|---|---|
| Rings | Punched sheets thread onto metal rings that open and close: ring binders, lever arch files, and sheet protectors that go into them. | Reference sets, coursework and manuals that change page by page. |
| Folders | Sheets sit loose inside folded board or plastic: file folders, file jackets, hanging folders, pocket folders, expanding files, wallets and file boxes. | Drawer filing, paperwork in transit, and anything you will not punch. |
| Display books | A display book binds a fixed number of clear sleeves; you slide pages in but cannot add sleeves. | Portfolios, presentations and certificates shown page by page. |

## How an expert narrows the choice

```mermaid
timeline
  section 1 · How it holds pages
    rings : ask How much it must hold, Ring shape, Page size and hole pattern : skip Folder tab cut, Folder expansion, Folder board thickness, Number of sleeves
    folders : ask Product type, Page size and hole pattern, Folder expansion : skip Ring shape, Ring size, Number of sleeves
    display book : ask Number of sleeves : skip Ring shape, Ring size, Folder tab cut, Folder expansion
  section 2 · How much it must hold
    over 500 sheets : ask Ring shape
  section 3 · Page size and hole pattern
    Letter, legal, A4, A5, or half-letter pages?
  section 4 · Safe for keepsakes
    yes : ask Cover and sleeve material
```

1. **How it holds pages.** Punched into rings, loose in folders, or a bound display book?
   The mechanism decides which facets apply at all, and the trade divides the range this way (Leitz files ring binders, suspension files, folders and display books separately).
   If rings: ask How much it must hold, Ring shape, Page size and hole pattern; skip Folder tab cut, Folder expansion, Folder board thickness, Number of sleeves.
   If folders: ask Product type, Page size and hole pattern, Folder expansion; skip Ring shape, Ring size, Number of sleeves.
   If display book: ask Number of sleeves; skip Ring shape, Ring size, Folder tab cut, Folder expansion.

2. **How much it must hold.** Under 200 sheets, a few hundred, or over 500?
   Capacity sets ring size and, above about 500 sheets, rules out round rings. Asking in sheets avoids the ring-size trap, because the same stated size holds different amounts by ring shape.
   If over 500 sheets: ask Ring shape.
   Skip if already known: ring_size_stated.

3. **Page size and hole pattern.** Letter, legal, A4, A5, or half-letter pages?
   A hard fit: the wrong size overhangs or rattles, and the wrong hole pattern does not go on the rings. Smead sells most folders in both letter and legal, so size is a variant to pick.
   Skip if already known: shopper_country, earlier_paper_size.

4. **Safe for keepsakes.** Keeping originals for years, like photos or certificates?
   Keepsakes need PVC-free plastics and acid-free board, which removes vinyl binders and sleeves. Most buyers can answer at once; for everyday paperwork it stops mattering.
   If yes: ask Cover and sleeve material.

## What to surface

### How it holds pages

Whether sheets are punched onto rings (sheet protectors included, since they go on rings), held loose in a folder or pocket, or slid into a display book's bound sleeves. It decides what you can do with the pages afterwards. Rings keep order and let you add, remove and reorder single sheets, but every page must be punched or sleeved. Folders take anything instantly, but pages shuffle and loose folders need a drawer or box. Display books protect and present pages but hold a fixed number. [17] [19] [3] [27]

Values: rings, folders, display book.
Question to ask: Punched into rings, loose in folders, or a bound display book?

Used as: top-level split, filter. Data: derived from listing fields, backfill cost none. Look for it as: Follows from the product type in the title (binder, lever arch, folder, file, display book).
Map from `format`.

### Page size and hole pattern

The paper size the product is made for, which in ring products fixes the hole pattern too. Letter binders take three holes 4.25 in (108 mm) apart, and half-letter has its own closer three-hole pattern. A4 takes two holes 80 mm apart (ISO 838) or four at 80 mm; four-hole pages fit two-ring binders, but not the reverse. A5 ring books often use four holes. Otherwise the patterns do not interchange. Folders come in letter and legal, and legal needs legal-size drawers. [1] [2] [3] [29] [5] [4] [18] [19]

Values: US letter, US legal, A4 two-hole, A4 four-hole, half-letter, A5.
Question to ask: Letter, legal, A4, A5, or half-letter pages?

Used as: top-level split, filter. Data: needs research, backfill cost low. Look for it as: Title or size option ("Letter", "Legal", "A4"); ring count often in the title for A4 (2-ring, 4-ring). Few US binder titles state it (7 of 48 Amazon titles).
Default by market (letter in North America, A4 elsewhere) only when nothing is stated, and mark it as assumed.
Chart: Hole pattern ruler.

### Safe for keepsakes

Whether every surface touching the pages is a stable plastic or acid-free board, with no PVC. The National Archives lists PVC under materials to avoid, and the Library of Congress lists only polyester, polyethylene and polypropylene as suitable plastics. Keepfiling, a sleeve seller, adds that PVC sleeves can lift laser print. For photos, look for the Photographic Activity Test (ISO 18916). Everyday paperwork does not need any of this. [7] [6] [9] [10] [27] [8]

Question to ask: Keeping originals for years, like photos or certificates?

Used as: top-level split, filter. Data: needs research, backfill cost medium. Look for it as: Description text: "PVC-free", "acid-free", "archival safe", "passes PAT".
Derive from cover and sleeve material; vinyl means no. Treat unstated as unknown, not safe.

### How much it must hold

The number of sheets the buyer needs to fit, banded; sheet protectors and dividers take more space than bare sheets. It sets ring size, and asking in sheets avoids the trap that one ring size holds different amounts by ring shape. Above about 500 sheets round rings stop being an option: the two retailer charts top them out at 460 and 510 to 570 sheets at 3 in, while D-ring binders come up to 5 in and lever arch files hold 350 to 600 A4 sheets. [15] [16] [13] [17] [5]

Values: under 200 sheets, 200 to 500 sheets, over 500 sheets.
Question to ask: Under 200 sheets, a few hundred, or over 500?

Used as: top-level split, filter. Data: derived from listing fields, backfill cost low. Look for it as: Band the stated capacity where the title gives it; else look up ring size and ring type in the capacity chart.
Use `sheet_capacity`; else the lower of the two charted capacities for that ring size and type, marked as estimated.
Chart: Ring capacity chart.

### Build tier

How a range is built for wear: economy, durable or heavy-duty, judged by board thickness, reinforced hinge and edges, cover width and ring openers. Avery ladders its range for light, frequent and extended use. Economy has standard board and two pockets. Durable adds thick board, a hinge and edges built not to tear or split, and covers wide enough for sleeves and tabs. Heavy-duty adds the thickest board, one-touch ring openers and four pockets. Ring shape follows the tier only loosely: Avery's chart pairs durable with slant rings, but its 09701 Durable View binder has EZD rings. [13] [12] [14]

Values: economy, durable, heavy-duty.
Question to ask: Light use, frequent use, or heavy long-term use?

Used as: filter, shown on the card. Data: needs research, backfill cost medium. Look for it as: Title words ("Heavy-Duty", "Durable", "Economy") on Avery and store brands.
Brand vocabulary differs; classify from hinge, board and ring-opener claims in the description.

### Product type

The specific filing product: ring binder, lever arch file, display book, file folder, hanging folder, pocket folder, expanding file, wallet, sheet protector or file box. Within a family the types do different jobs. Hanging folders hold manila folders on drawer rails rather than loose sheets. File jackets have closed sides so papers do not slip out in transit. Lever arch files stand on a shelf and hold the most A4 per file. Sheet protectors are an accessory that goes into rings. [17] [19] [18] [5] [27]

Values: ring binder, lever arch file, display book, file folder, file jacket, hanging folder, pocket folder, expanding file, document wallet, sheet protector, file box.
Question to ask: For a file drawer, carrying around, or a storage box?

Used as: filter. Data: on the listing, backfill cost low. Look for it as: Product noun in the title.
Classify from title words; photos settle the rest.

### Clear-view cover

A clear overlay pocket on the front, back and spine that takes a printed cover sheet and spine label. It lets you retitle the binder later without labels, which is why teachers ask for it and why presentation binders use it. Without it, shelf identification depends on stick-on spine labels. [14] [12] [28]

Question to ask: Want a clear cover to slip a title page into?

Used as: filter. Data: on the listing, backfill cost none. Look for it as: Title words View, Clear View or ClearVue (19 of 48 Amazon binder titles); the product photo shows the overlay.
When the title is silent, the product photo shows the clear overlay.

### Ring size

The stated ring diameter in inches, the 1 in or 3 in in the title; Ring Binder Depot says D-rings are measured along the straight side. It is the number every title leads with, but on its own it does not say how much fits. Read it with ring shape, or use the sheet capacity. It also sets the spine width and so shelf space, which brands state separately. [3] [11] [12] [16] [28]


Used as: shown on the card, sortable. Data: on the listing, backfill cost none. Look for it as: Title, as 1", 1-1/2", 2" and so on. Lever arch files give a spine width in mm instead.
Chart: Ring capacity chart.

### Ring shape

The shape of the metal rings: round (O), straight D, slant D, or a lever arch mechanism. At the same stated size D-rings hold more than round rings: Ring Binder Depot says up to 30 percent, Avery up to 50, and Unikeep's chart implies 44 to 57. D-rings sit on the back cover, so pages lie flat; round rings sit on the spine. Straight D holds slightly more than slant D; two retailers call slant D more durable. Lever arch mechanisms, two-ring and A4, are their own scale. [11] [13] [15] [16] [17] [28]

Values: round, straight D, slant D, lever arch.

Used as: filter, shown on the card. Data: on the listing, backfill cost low. Look for it as: Most retail titles name it as D-Ring, Slant-D, EZD, O-Ring or Round Rings (32 of 48 Amazon binder titles).
Brand spec blocks state it; photos show ring shape.
Chart: Ring capacity chart.

### Stated sheet capacity

How many sheets the maker says the binder or folder holds and still closes. It is the honest version of ring size when it is right, but stated figures are loose and brands disagree. Avery's page for one 3 in binder gives both 670 and 400 sheets, and Cardinal's round-ring titles state 208 to 237 sheets per inch where the two retailer charts give 153 to 190. Compare like with like, and treat a figure far from the charts as a prompt to check. [11] [12] [15] [16] [28]


Used as: filter, sortable. Data: needs research, backfill cost low. Look for it as: In about half of Amazon binder titles ("Holds 350 Sheets") and in brand spec blocks; rarely for folders.
Estimate from the capacity chart for its ring size and type when missing, and mark it as estimated.
Chart: Ring capacity chart.

### Number of sleeves

How many clear sleeves a display book has bound in. A bound display book cannot grow, so the count is the page limit, front and back of each sleeve: Itoya's 24-sleeve book, riveted to the cover, takes 48 inserts. Buy for the longest set you will show. [27] [17]

Question to ask: About how many pages will it show?

Used as: filter. Data: needs research, backfill cost low. Look for it as: Brand pages state it ("24 pages for 48 views"); retail titles not confirmed.
Brand pages state it.

### Cover and sleeve material

What the cover, pockets and any sleeves are made of: polypropylene, PVC vinyl over board, paperboard or pressboard, or fabric or leather. It decides archival safety and whether print sticks to the plastic. Polypropylene is the stable, PVC-free choice. Vinyl over board is the classic binder build and the one archivists avoid for keepsakes; since July 2020 the EU has barred four phthalate plasticisers at 0.1% or more of PVC and other plasticised parts. Board and pressboard are paper, so acid-free matters for long storage. [13] [3] [9] [7] [6] [20] [21] [22]

Values: polypropylene, PVC vinyl, paperboard or pressboard, fabric or leather.

Used as: filter, shown on the card. Data: needs research, backfill cost medium. Look for it as: Material line in the description or spec table; often only "poly" or "vinyl".
Brand pages usually say. For the top N only when the buyer has said yes to keepsakes.

### Folder tab cut

How wide the label tab on a folder is as a share of the folder's length: straight, 1/2, 1/3, 2/5 or 1/5. The cut sets how many tab positions stagger across a drawer, so labels do not hide each other. Narrow cuts fit more positions; straight cuts give the most label room. [19] [18]

Values: straight, 1/2, 1/3, 2/5, 1/5.

Used as: filter. Data: needs research, backfill cost low. Look for it as: Title on Smead pages ("1/3-Cut Tab"); retail titles not confirmed.
Brand pages state it; photos show the tab.
Chart: Tab cut strip.

### Folder expansion

How far the folder opens at the fold, in inches, from scored creases or a box bottom. Smead's standard scored folders open 3/4 in, its file jackets and box-bottom folders 1 to 3 in, and its expanding files further still. Overfilling a folder past its expansion bends the papers and the tab. [18]


Used as: filter, shown on the card. Data: needs research, backfill cost low. Look for it as: Description ("Scored for 3/4\" expansion", "Expands 2\"").
Brand pages state it; assume 3/4 in for plain scored folders only when the brand page says scored.

### Folder board thickness

The thickness of a folder's board in points (thousandths of an inch). It is the number a folder maker gives for how long a folder lasts in use. Smead sells 11 pt stock for files that are seldom accessed and heavier stock for files pulled often. [18]


Used as: shown on the card. Data: needs research, backfill cost medium. Look for it as: Description ("11 point stock").
Brand pages only; backfill for the top N folders.

## Numbers worth computing

| Metric | Formula | Why |
|---|---|---|
| Sheets per inch of ring (sheets per in) | `sheet_capacity / ring_size_in` | Compares stated capacities like for like. Across the two retailer charts round rings run 153 to 190 sheets per inch and D-rings about 195 to 320, falling per inch at 3 in and up, while Cardinal states 208 to 237 for its round rings. A figure far outside the charts is a prompt to check, not a verdict. [15] [16] [28] |
| Ring size needed (in) | `smallest stocked ring size whose charted capacity for ring_type is at least sheets_to_hold, using the lower of the two retailer charts` | Turns the buyer's sheet count into the size to search for. 500 sheets fits a 2 to 2.5 in D-ring binder; in round rings it needs 3 in by Ring Binder Depot's chart (510 to 570) and does not fit by Unikeep's (460). A straight per-inch rate overstates rings of 3 in and up. [15] [16] [14] |
| Price per 100 sheets of capacity (currency per 100 sheets) | `price / sheet_capacity * 100` | Compares a cheap round-ring binder with a dearer D-ring one that holds more at the same size. [15] |

## What you give up

- Retailers and Avery agree D-rings hold the most per ring size, and D-ring binders come up to 5 in. Leitz pitches slim ring binders for carrying and lever arch files for the shelf. [14] [13] [26] [17] [15] Board branch: "See more slim binders to carry".
- Round rings are the economy build and sit on the spine, so the stack curves and pages do not lie flat. D-rings on the back cover lie flat but are sold in dearer tiers. [15] [16] [13] Board branch: "See more binders whose pages lie flat".
- Rings hold every sheet in place and let you reorder, at the cost of punching or sleeving each page. Folders and jackets take papers as they come; closed-sided jackets stop them slipping out. [18] [3] Board branch: "See more no-punch options".
- Sheet protectors keep pages clean but take more ring space than bare paper, and Keepfiling, a sleeve seller, says PVC sleeves can lift print. Polypropylene sleeves avoid the second problem. [5] [9] [10] Board branch: "See more PVC-free sleeves".

## How to draw it

**Ring capacity chart** (bar, shows Ring size, Ring shape, Stated sheet capacity, How much it must hold). Grouped bars of sheets by ring size, one colour per ring shape, show at a glance that a 2 in D-ring holds about what a 3 in round ring does. Used today by Binder retailers and makers publish this table (Unikeep, Ring Binder Depot); Avery prints capacity beside ring size.. [15] [16]

**Hole pattern ruler** (scale, shows Page size and hole pattern). Hole positions drawn along a page edge make it obvious why three-hole letter pages will not go on two-ring A4 binders. Used today by ISO 838 draws the two-hole layout; Wikipedia's hole punch article keeps a hole spacing chart.. [1] [2]

**Tab cut strip** (other, shows Folder tab cut). A row of folder tops showing each cut's tab positions shows how labels stagger in a drawer. Used today by Folder makers name cuts and positions this way (Smead); a proposal as a drawing.. [19] [18]

## Words you will meet

- **Ring size**. The diameter of a binder's rings in inches, which is not the same as how many sheets it holds.
- **Round ring (O-ring)**. A circular ring fixed to the spine; the cheapest kind, and pages do not lie flat.
- **D-ring**. A ring with one flat side, fixed to the back cover, that holds more and lets pages lie flat.
- **Slant-D ring**. A D-ring set at an angle, between round and straight D in capacity.
- **Lever arch file**. A stiff upright file with a two-ring lever mechanism, the standard office file in A4 countries.
- **One-touch booster**. A tab at the end of the rings that opens all of them with one press.
- **View binder**. A binder with a clear plastic overlay on the cover and spine for a printed insert.
- **Sheet protector (punched pocket)**. A clear, pre-punched plastic sleeve that holds one sheet inside a ring binder.
- **Display book**. A book of clear sleeves bound in, so pages slide in but sleeves cannot be added.
- **ISO 838**. The international standard for two filing holes 80 mm apart, used with A4 paper.
- **888 punching**. Four holes each 80 mm apart, which fit both four-ring and two-ring A4 binders.
- **PVC (vinyl)**. A soft plastic common in cheap binders and sleeves that archivists avoid for keepsakes.
- **Photographic Activity Test (PAT)**. An ISO test (ISO 18916) that checks whether a storage material harms photographs.
- **Tab cut**. The width of a folder's label tab as a share of its length, such as 1/3.
- **Hanging folder**. A folder with hooks that hang on rails inside a drawer and hold ordinary folders.
- **File jacket**. A folder with closed sides so papers cannot slide out.
- **Point (pt)**. A thousandth of an inch, the unit for folder board thickness.
- **Phthalate**. A softening chemical (plasticiser) added to PVC; the EU restricts four of them in everyday articles.

## Where we made a call

- At the same ring size, D-rings hold more than slant-D, and slant-D more than round rings. (confidence high). Sources disagree. All agree on the order but not the gap: Ring Binder Depot says up to 30 percent, Avery up to 50, and Unikeep's chart implies 44 to 57. We give about 30 to 50 percent. [16] [15] [11] [13]
- Stated sheet capacities are approximate and sometimes contradictory, so check them per ring inch. (confidence medium). Avery's 09701 page states 670 and 400 sheets for one binder, and Cardinal's round-ring figures run above both retailer charts. Ring Binder Depot's figures are where the binder closes comfortably. [12] [28] [16] [15]
- PVC binders and sleeves are unsuitable for keeping photos or important originals long term. (confidence high). The National Archives lists PVC to avoid; the Library of Congress lists only polyester, polyethylene and polypropylene as suitable. Keepfiling, a seller, says PVC lifts print; Avery says only that its own polypropylene does not. [7] [6] [9] [11]
- Letter and A4 are different sizes with different hole patterns, and one region's binders do not take the other's pages. (confidence high). Sources disagree. Avery's FAQ calls 8.5 by 11 in paper A4, which is wrong; A4 is 210 by 297 mm. We follow ISO 838 and the Wikipedia dimensions. [1] [2] [4] [13]
- US hole patterns are custom, not a formal standard, and ISO 838 itself excludes loose-leaf binders. (confidence medium). The ISO text says so and records the US objecting; Wikipedia finds no formal ANSI hole standard. Small differences in hole size rarely matter in practice. [1] [2]
- Chemical limits apply: the EU has capped four phthalates in PVC and other plasticised parts since July 2020, and US children's products cap lead. (confidence high). REACH entry 51 bars DEHP, DBP, BBP and DIBP at 0.1% or more of the plasticised material; ECHA names office supplies. The US 100 ppm lead limit reaches only binders designed or marketed for children 12 and under; that scope reading is ours. [20] [21] [22] [23] [24] [25]

## References

1. [ISO 838:1974 Paper: holes for general filing purposes (preview)](https://cdn.standards.iteh.ai/samples/5207/c7c11e2022304b368909f866a90a5c7b/ISO-838-1974.pdf) (standards body). Supports: Two holes 80 mm apart, 6 mm diameter, 12 mm from the edge; Does not apply to loose-leaf binders; the USA disapproved.
2. [Wikipedia: Hole punch (Standards)](https://en.wikipedia.org/wiki/Hole_punch) (primer). Supports: US letter three holes 4.25 in (108 mm) apart; legal four holes 89 mm; 888 four-hole pattern fits two-ring binders too; No formal ANSI hole standard; US patterns are de facto.
3. [Wikipedia: Ring binder](https://en.wikipedia.org/wiki/Ring_binder) (primer). Supports: North American spacing 4.25 in (108 mm); ISO two holes 80 mm; Leitz invented the lever arch file; Covers are board wrapped in vinyl or other materials.
4. [Wikipedia: Punched pocket](https://en.wikipedia.org/wiki/Punched_pocket) (primer). Supports: A4 is 210 by 297 mm; US letter 216 by 279 mm; Most sheet protectors are polypropylene.
5. [Wikipedia (German): Aktenordner](https://de.wikipedia.org/wiki/Aktenordner) (primer). Supports: 80 mm lever arch holds about 600 sheets of 80 g/m²; 55 mm about 350; Dividers and sleeves reduce how many sheets fit.
6. [Library of Congress: How do I preserve my photographs and negatives?](https://ask.loc.gov/preservation/faq/422212) (regulator). Supports: Suitable plastics: uncoated polyester, polyethylene, polypropylene; Storage materials should pass the Photographic Activity Test; Polypropylene sleeves in ring binders are an easy solution.
7. [US National Archives: Storing family papers and photographs](https://www.archives.gov/preservation/family-archives/storing) (regulator). Supports: PVC plastics listed under materials to avoid; Sleeves of polyester, polypropylene or polyethylene; boxes acid-free and lignin-free.
8. [Wikipedia: Photographic Activity Test](https://en.wikipedia.org/wiki/Photographic_Activity_Test) (primer). Supports: PAT is ISO 18916, formerly ISO 14523.
9. [Keepfiling: Archival safety and what sheet protectors are made of](https://www.keepfiling.com/archival-safety-a/134.htm) (other). Supports: PVC contains plasticisers and is not recommended for archival storage; PVC sleeves can pick up laser print.
10. [Avery: Polypropylene sheet protectors are archival safe](https://www.avery.com/help/article/averys-polypropylene-sheet-protectors-are-archival-safe) (spec sheet). Supports: Polypropylene is pH neutral and contains no plasticisers.
11. [Avery 79812 Heavy-Duty View binder, 4 in EZD rings](https://www.avery.com/products/binders/79812) (spec sheet). Supports: 4 in EZD D-ring holds 780 sheets; EZD rings hold up to 50 percent more than round rings; Back-mounted rings keep pages flat; its polypropylene won't lift toner.
12. [Avery 09701 Durable View binder, 3 in EZD rings](https://www.avery.com/products/binders/09701) (spec sheet). Supports: The same page states 670 and 400 sheets for one 3 in binder; A Durable View binder sold with EZD rings; PVC-free pockets won't transfer ink.
13. [Avery binders category, FAQ and comparison chart](https://www.avery.com/category/products/binders/) (spec sheet). Supports: Economy, Durable, Heavy-Duty for light, frequent and extended use; board standard to thickest; Wider panels on Durable and Heavy-Duty cover sheet protectors and tabs; rings up to 5 in; Wrongly calls 8.5 by 11 in paper A4.
14. [Avery: The best binders for school](https://www.avery.com/blog/the-best-binders-for-school-at-every-age-and-level/) (spec sheet). Supports: A 2 in binder with 500-sheet capacity covers most textbooks; Hundreds of sheets get heavy; durable builds suit them; Teachers ask for view binders.
15. [Unikeep: 3 ring binder sizes chart](https://www.unikeep.com/binder-sizes-chart/) (retail listing). Supports: Round 1 in 175, 3 in 460 sheets; D 3 in 670, 4 in 780; D up to 5 in; Slant-D is more durable but holds less than straight D; Round rings on the spine; pages do not lie flat.
16. [Ring Binder Depot: How to choose the right 3 ring binder](https://ringbinderdepot.com/blogs/articles/how-to-choose-the-right-3-ring-binder) (retail listing). Supports: Round 1 in 170 to 190, 3 in 510 to 570; D 1 in 225 to 240; D holds up to 30 percent more than round; slant-D about 5 percent less than D; D-ring size measured along the straight side.
17. [Leitz UK: lever arch files, ring binders and filing range](https://www.leitz.com/en-gb/products/filing--archiving/lever-arch-files/) (spec sheet). Supports: Lever arch files hold 350 to 600 A4 sheets; Filing range divided into lever arch, ring binders, suspension files, folders, display books.
18. [Smead file folders, hanging folders and expanding files (product data)](https://www.smead.com/products/standard-file-folders-1-3-cut-tab) (spec sheet). Supports: Folders listed by letter or legal size, tab cut, point stock and expansion; Standard 11 pt folders scored for 3/4 in; jackets expand 2 in; Most folders come in both sizes: letter on 124, legal on 89, both on 76 of 143.
19. [Wikipedia: File folder](https://en.wikipedia.org/wiki/File_folder) (primer). Supports: Letter and legal are the common US sizes; Tab cuts: straight, 1/2, 1/3, 2/5, 1/5; Hanging folders hold manila folders, not loose sheets.
20. [Commission Regulation (EU) 2018/2005, REACH Annex XVII entry 51 (four phthalates)](https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:32018R2005) (regulator). Supports: From 7 July 2020, four phthalates barred in articles at 0.1% or more of plasticised material; Plasticised material includes PVC; exemptions are industrial, outdoor, vehicle, aircraft and similar uses.
21. [European Chemicals Agency: Phthalates](https://echa.europa.eu/hot-topics/phthalates) (regulator). Supports: DEHP, DBP, DIBP and BBP restricted since July 2020 in products including office supplies.
22. [Wikipedia: Phthalates (regulation)](https://en.wikipedia.org/wiki/Phthalates) (primer). Supports: Since 7 July 2020 REACH entry 51 limits four phthalates to 0.1% in all articles.
23. [15 U.S.C. 1278a: Children's products containing lead](https://www.law.cornell.edu/uscode/text/15/1278a) (regulator). Supports: Children's products limited to 100 ppm total lead in any part.
24. [US Consumer Product Safety Commission: Total lead content](https://www.cpsc.gov/Business--Manufacturing/Business-Education/Lead/Total-Lead-Content) (regulator). Supports: Children's products over 100 ppm lead in an accessible part are a banned hazardous substance.
25. [16 CFR 1200: Definition of children's product](https://www.ecfr.gov/current/title-16/chapter-II/subchapter-B/part-1200) (regulator). Supports: Children's products are designed or intended primarily for ages 12 and under; Items found in schools count only if themed, child-sized or marketed to children.
26. [Leitz UK: ring binders](https://www.leitz.com/en-gb/products/filing--archiving/ring-binders/) (spec sheet). Supports: Slimline ring binders are convenient to carry; Two- and four-ring varieties.
27. [Itoya: Art ProFolio Advantage presentation book](https://itoya.com/collections/profolio) (spec sheet). Supports: 24 sleeves riveted to the cover take up to 48 inserts; Acid-free and PVC-free.
28. [Amazon US search results for 3 ring binder](https://www.amazon.com/s?k=3+ring+binder) (retail listing). Supports: Of 48 binder titles, ring type in 32, View in 19, sheet capacity in 23; Cardinal round-ring titles state 225 sheets at 1 in to 625 at 3 in.
29. [Hole punch measurements (unattributed web PDF)](https://img1.wsimg.com/blobby/go/db112521-e536-400b-b453-631e78951ba0/downloads/78851783429.pdf) (other). Supports: US 3-hole letter holes 108 mm apart; 888 holes 80 mm apart; Four-hole 888 pages also fit two-ring binders.