EWLINE Spine capacity Inches Millimeters Sheets of paper 3/16" 4mm 16 1/4" 6mm 25 5/16" 8mm 40 3/8" 10mm 55 7/16" 11mm 70 1/2" 12mm 85 9/16" 14mm 100 5/8" 16mm 125 3/4" 20mm 150 7/8" 22mm 175 1" 25mm 200 1⅛" 28mm 250 1¼" 32mm 275 1½" 38mm 325 1¾" 45mm 375 2" 51mm 425

Comb binding (sometimes referred to as "cerlox binding") is one of many ways to bind

Bookbinding

Bookbinding is the process of physically assembling a book from a number of folded or unfolded sheets of paper or other material. It usually involves attaching covers to the resulting text-block.-Origins of the book:...

 pages together into a book. This method utilizes round plastic spines with 19 rings (for US Letter size) or 21 rings (for A4 size) and a hole puncher that makes rectangular holes. Comb binding is sometimes referred to as plastic comb binding or spiral comb binding.

Binding process

To bind a document, the user first punches holes in the paper with a specialized hole punch

Hole punch

A hole punch is a common office tool that is used to create holes in sheets of paper, often for the purpose of collecting the sheets in a binder or folder.The origins of the hole punch date back to Germany via Matthias Theel, where two early patents for a...

. Pages must be punched a few at a time with most of these machines. If hard covers are desired, they must be punched as well. In bulk applications, a paper drilling machine may be used.

Then the user chooses a spine size that will match the document. Standard sizes are 3/16 inch (for 10 sheets of 20# paper) up to 2 inches (for 425 sheets). Spine lengths are generally 11 inches to match the length of letter-size paper.

The rings on the spine open and insert into the holes in the page, then rest against the body of the spine, resulting in a closure that can be opened again for making changes to the book.

Comparison with other punch binds

With this bind, the book lies flat but cannot be opened 360 degrees. For a book that can be opened such that the covers touch, a spine that does not have an obstructive body, such as a coil binding

Coil binding

Coil binding, also known as spiral binding, is a commonly used book binding style for creating documents, reports, presentations and proposals. This binding style is known by a number of names including spiral coil, color coil, colorcoil, ez-coil, plastic coil, spiral binding, plastikoil and...

, is a better option.

Machine opening the spine	Pre-punched paper with spine rings through holes
Rings closed on paper	Completed book out of machine