Ring Binder Mechanisms


At Duraweld, we use three different mechanisms when it comes to our ring binders: D Ring, O Ring and Lever Arch.

In this article, we’ll break down: what the different mechanisms look like, what they’re best used for and how they’re sized. For simplicity, we’ve only included the three most commonly used mechanisms. As a specialist supplier however, if there is a mechanism you require our sales team is more than happy to help discuss your needs further.

Mechanism styles and shape

Style and Shape

'D' Ring

The D-ring named as it is shaped like a backwards ‘D’ is by far the most popular shape of mechanism we supply, with the flat edge keeping your paperwork in a neat flush stack.

The mechanism is fitted into the back cover, with the rivets less noticeable and keeping the spine clear for artwork and print. This also allows the front cover to be opened and closed without moving your documents, as found when using the O-ring, minimising any pull and tear along the punch holes of your contents.

This shape of ring is suitable for the majority of ring binders; archiving, presentation, display books, handbooks, training manuals, reference materials, student notes and more.

'O' Ring

The O-ring or round mechanism, named because of its O like shape, is usually fitted into the spine of the ring binder. This type of mechanism is best suited for easel binders as its spine fixing location allows the pages to turn easily. Any print or pockets on the spine will have to be designed to avoid the rivets.

Lever Arch

Lever arch mechanisms are fitted into the back cover of the binder. The lever action allows it to be opened and closed easily allowing for quick and easy organisation of your contents. 

This style of mechanism is often supplied with a compressor bar that allows the document stack to be clipped securely to minimise movement. Like the D-ring it has a flat edge providing the same benefits. 

This style of mechanism is often favoured by legal and account firms or departments due to the increased capacity as well as its ease of use.

Ring binder mechanism lever arch

How we measure

Two key measurements of any mechanism are its capacity and ring spacing, measured in millimetres.

  • We measure the capacity based on the gap between the mechanism base plate and the usable vertical length of the ring before it curves around at the top.

  • The ring spacing is the distance between the rings of the mechanism with various standards utilised across the wide range of mechanisms available. This spacing can also be referred to as the hole punch spacing.

A ring binder’s capacity can easily get confused with the size of the spine which is larger to fit round the mechanism. One way to think of it is;

  • The capacity is how much the binder can hold.

  • The spine size is how much space it takes up on the shelf.

Number of Rings

Two Rings

Two ring mechanisms are the most economic and also the most suitable for use when simple additions to the binder are envisaged (most offices use a two hole punch). They are not suitable for heavy use, since the pages are more likely to tear out.

Ring binder mechanism 2 rings

Three Rings

Three ring mechanisms are mostly used when the binder contains pages going to or from the United States - nearly all loose-leaf supplies in the USA are based on three rings. Three rings also prevent the transfer of pages to and from other binders, since most will be two or four rings.

Four Rings

This form of fitting, keeps all the pages in line. It also has the least risk of tearing the pages in heavy use, as the pressure is shared between four ‘weak’ areas rather than two or three.

These measurements are particular to the type of mechanism’s capacity, style and the number of rings.

Ring binder mechanism 4 ring

Ring Spacing

Ring spacing, sometimes referred to the hole punch spacing, is the measurement of the gaps between the rings of the mechanism along its length.

The spacing is displayed below as an image to give a quick overview of the measurements based on the hole punches within your documents.

Ring binder mechanism ring spacing guide

Custom Orders
Custom Orders

Want to know more? Get in touch. Talk to us