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Letter Size 3-Ring Binder Mechanisms (Price per Box)


Sometimes called ring binder parts or ring binder hardware, ring mechanisms are the spine pieces found on the inside of ring binders. These ring binder spines are letter size for standard 8 ½" x 11" sheets. They feature three rings with standard 4 ¼" spacing between the rings, two boosters for easy ring opening, and holes on each end for use with binder rivets and a rivet setter tool.

Ring binder mechanisms are a popular solution for making your own custom binders, unique display swatches, and much more. You can buy letter size 3-ring binder mechanisms online in ring sizes from 1/2" up to 4", some sizes available in both round and slant-d ring style options. All sizes are available in silver mechanisms, and several sizes are also available in black and brass colors. We sell ring binder mechanisms in full boxes; depending on the color and ring size, the quantity per box will vary. Make a selection below to see the packaged quantities.

Starting at: $41.50
Qty/Pack : Make a selection above to see pieces per box

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Capacity Chart

The best way to measure the capacity for a ring binder or ring binder mechanism is to use a stack thickness. To do so, allow your entire stack of paper, tabs, etc. to lay flat, without pressing them down, and measure the height of the stack. We also list an approximate sheet capacity, however, because there are so many different kinds of papers and paper thicknesses, this is a less accurate method of determining capacity. The sheet capacity below is based on standard 20 lb. copy paper alone.

Ring SizeColors AvailableSheet Capacity*Stack Capacity*
1/2" Silver & Black 110 Sheets 1/4" Thick Stack
3/4" Silver & Brass 150 Sheets 3/8" Thick Stack
1" Silver, Black, & Brass 200 Sheets 5/8" Thick Stack
1 ½" Silver, Black, & Brass 310 Sheets 1" Thick Stack
2" Silver & Brass 450 Sheets 1 ½" Thick Stack
2 ½" Silver 540 Sheets 2" Thick Stack
3" Silver 650 Sheets 2 ½" Thick Stack
4" Silver 850 Sheets 3 ½" Thick Stack

Binder Mechanism FAQs

Q: What capacity are the rings?
Sheet capacities vary depending on the ring size you choose. View the Chart in the product description for details.


Q: Do you have slant-d mechanisms?
Slant-D style rings are available on select sizes of the silver mechanisms.


Packaged Quantities

Ring SizeColorQty / Box
1/2" Silver 50 pcs
Black 200 pcs
3/4" Silver 50 pcs
Brass 200 pcs
1" Silver 50 pcs
Black 208 pcs
Brass 160 pcs
1 ½" Silver 50 pcs
Black 144 pcs
Brass 192 pcs
2" Silver 50 pcs
Brass 54 pcs
2 ½" Silver 50 pcs
3" Silver 50 pcs
4" Silver 50 pcs

Product Description


Letter size ring binder mechanisms are the spine piece found on the inside of ring binders and work for 8 ½" x 11" standard letter sized papers. They feature 3-rings with traditional ring spacing of 4 ¼" between each ring, so work seamlessly with any traditional 3-hole punch. Use ring binder spines as a way to securely bind loose, hole-punched pages, or as a unique way to create swatch books and custom ring binders. You can pair with our binder rivets and rivet setter tool to bind the ring binder hardware onto a custom chip board sheet.

These metal binder parts are available in three colors: silver, black, and brass. Traditional silver binder mechanisms are available in the full range of ring sizes from 1/2" up to 4", many of those sizes also available in either round ring or slant-d ring options. They offer the most versatility, and are our most popular option because of their traditional and clean look, as well as their packaging with 50 mechanisms per box. Black and brass colored binder mechanisms are available in select sizes from 1/2" to 2", all with round ring styles. The packaging for colored ring binder spines varies depending on the ring size, but all you have to do is make a selection above to see the quantity per box. All colors are made of a durable metal material, and feature two boosters for easy ring opening and closing, as well as holes on each end that allow use with our binder rivets for binding the spine onto an item of your choice.

Below is a ring binder capacity chart that will help you determine what size ring you need, depending on the thickness of materials you need to bind. The sheet capacity is an approximation that was determined using standard 20 lb. bond copy paper; so please keep this in mind when looking at your own sheets. We have also rated each size with a "stack capacity" which is more accurate and won't change depending on the materials you are binding, because a 1" stack of 20 lb. paper is the same thickness as a 1" stack of 110 lb. index stock.

Ring SizeColors AvailableSheet Capacity*Stack Capacity*
1/2" Silver & Black 110 Sheets 1/4" Thick Stack
3/4" Silver & Brass 150 Sheets 3/8" Thick Stack
1" Silver, Black, & Brass 200 Sheets 5/8" Thick Stack
1 ½" Silver, Black, & Brass 310 Sheets 1" Thick Stack
2" Silver & Brass 450 Sheets 1 ½" Thick Stack
2 ½" Silver 540 Sheets 2" Thick Stack
3" Silver 650 Sheets 2 ½" Thick Stack
4" Silver 850 Sheets 3 ½" Thick Stack

* Sheet capacity is an approximation based on standard 20 lb. bond copy paper, and may vary depending on paper stock being used. Stack capacity is a more accurate alternative. To measure, place your entire stack of material on a flat surface and, without pressing the stack down, measure the thickness of the stack..


Manufacturer US Ring
Manufacturer Part Number RINGMECHSLET CFG
Quantity Make a selection above to see pieces per box
Sheet Size Letter Size [8 ½" W x 11" H]
Number of Rings 3-Rings
Ring Spacing 4 ¼" Between Rings [Center to Center]
Ring Shape Round Ring & Slant-D Ring Available
Sheet Capacity* [Stack Thickness] Varies Depending on Ring Size
Boosters Yes

Expert Reviews

Expert Reviewer: Mallory, Editor at Binding101Expert Product Review: 3-Ring Binder Mechanisms  by Mallory Morsa
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Hi everyone! My name is Mallory Morsa, and I am the product expert at Binding101. I have been a part of the Binding101 team since 2008, where I started out in service and sales, learning our customers' needs and how to offer truly exceptional service. After a of couple years, I moved into a role of product management that required in-depth product research, as well as training of our staff. And in my honest expert reviews, I am proud to share that extensive knowledge with you. Take a look at the product review below, which will highlight both the pros and the cons, as well as identify the ideal customer. If you have any questions or need more information, please call our customer care team at (866)537-2244. Thank you for stopping by, and please check out our Binding101 social media channels by clicking the icons above.


Metal Binder Mechanism + 3-Ring Binder Parts Expert Review by Mallory Morsa


Binder mechanisms are popular for users of many kinds who want to make their own ring binders. Because they are sold in full boxes of 50+ mechanisms (depending on the size/color) our customers tend to be in the manufacturing, industrial supply, and government/military industries, however, sometimes home businesses that make custom binders to sell on Etsy will buy too. They are even used by furniture and fabric stores to hold swatches of fabrics as an alternative to loose leaf rings.

Binder mechanisms are great, because they give you complete control over making your own custom binder and other crafts. They are made of metal, and are very durable to withstand a lot of heavy use. They have boosters on the ends, which make opening the rings quick so you don’t have to pull the rings open by hand, and there are two holes in each mechanism for rivets, which when bound properly, will make a very strong attachment. They also come in several colors, so you can make your binders stand-out with gold/brass or black mechanisms, or keep a more traditional look with the silver ones.

These particular ring mechanisms are letter size, which is the most popular ring binder size in the US. The spacing is regular 3-ring spacing to be compatible with all standard 3-hole punches (like the ones available here). And because they are just the metal binder spine without the covers attached, they are extremely versatile. Use them to make traditional ring binders or unique clipboards, or use them to  hang calendars and organize items, or for anything else that you can think of. The pricing is also very reasonable per piece (especially the silver, considering you can probably not find them elsewhere for under $5 each), part of the benefit of selling full-case quantities.

There is a minimum order requirement for these mechanisms that makes them unobtainable by a lot of individuals or personal users, and even some small businesses. For silver mechanisms, it is 50 pieces for all the sizes. For black and brass mechanisms, the quantity varies depending on the ring size, ranging from 54 to 200 pieces. Unfortunately, we are unable to sell smaller quantity boxes, as these minimums are required by the manufacturer. They are also not available in assorted size boxes, so if you need 1" and 2" silver mechanisms, the minimum is 1 box per size.

Unless you have a large, automatic rivet setter machine for your industrial manufacturing plant, then riveting is done using a hand setter tool that can sometimes be tedious and difficult to use without the proper amount of strength. I am a fairly small woman, and it took several tries before I was able to accomplish a good finish that was tight enough to hold the mechanism in place properly. So before you buy, consider the fact that it can take quite a bit of effort and strength to rivet them to your binder covers and other materials, and consider standard pre-made ring binders as an alternative.

Also, although 3 colors are available, only silver is available in the full range of ring sizes from ½” to 4”, as well as round-ring and slant-d ring styles; the black and brass colors are only available with rings up to 2” in the round-ring style.

Ring binder mechanisms are a popular solution for businesses of many kinds, especially industrial and manufacturing plants, as well as government/military bases, and more. They are the standard size for the most popular paper size in the United States (8 ½” x 11”), come in a few cool colors, and several different ring sizes to handle stacks of paper and other materials up to 3 ½" thick. They are only sold in case-quantities (starting at 50 per case) and are unavailable in smaller boxes. Sometimes they can be a challenge to work with, but if you persevere, you can create a huge variety of unique ring binders and other items of all kinds.

User Reviews

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