Where does this come from, and can I check it?

A straight spine edge lets sheets lie level and packs more of them in. The figure is taken from US Patent and Trademark Office, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.

Is this really a everyday life fact?

Yes. It sits on the Everyday Life shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.

What else can I read about it?

The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.

Mondo Knows Facts

D-ring binders hold pages flatter than round rings

A straight spine edge lets sheets lie level and packs more of them in Round rings push pages into a curve and waste space at the spine. A D-ring has a straight back section, so the sheets sit flat against the cover and the rings hold more paper in the same cover width. The lever arch file uses the same idea with a curved mechanism and a finger hole for lifting it off a shelf. It sits in Mondo's everyday life collection, one of 200 facts that each trace back to the reference below.

Where this comes from

US Patent and Trademark Office

Facts that can change over time are reviewed and updated. If something here looks wrong, Mondo would rather know than be confidently incorrect.

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Office hole punches space holes 80 millimetres apartA filing standard fixes the distance so any sheet fits any binder A binder clip is one folded strip of steelThe looped handles are the spring, squeezed to open the jaws Hexagonal pencil barrels prevent pencils rolling off slanted desksFlat pencil sides improve grip and stop pencils from rolling onto floors Highlighters glow because the ink fluorescesA dye absorbs ultraviolet and violet light and re-emits it as visible colour The metal band on a pencil is a ferruleCrimped ridges grip both the wood barrel and the plug of rubber Envelope gum is a starch adhesive activated by waterDextrin from cooked starch turns tacky when the flap is moistened

Tags: stationery, offices, design

D-ring binders hold pages flatter than round rings: the short answers

Where does this come from, and can I check it?: A straight spine edge lets sheets lie level and packs more of them in. The figure is taken from US Patent and Trademark Office, which is linked in full on this page. Every fact on Mondo Knows names its source rather than repeating an unsourced claim.
Is this really a everyday life fact?: Yes. It sits on the Everyday Life shelf, one of 2,600 sourced facts grouped into space, animals, the human body, history, science and more. Category pages collect every fact in the same field.
What else can I read about it?: The links under the fact point to a quiz, game, puzzle or calculator on the same subject, and the shelf below shows related facts. The wording here is original, and quoted phrases are marked as quotations.