Comb binding
bind examples.JPG|thumb|right|Two spine sizes (the larger has the capacity to bind several hundred sheets)]
| Inches | Millimeters | Sheets of paper |
| " | 4 mm | 16 |
| " | 6 mm | 25 |
| " | 8 mm | 40 |
| " | 10 mm | 55 |
| " | 11 mm | 70 |
| " | 12 mm | 85 |
| " | 14 mm | 100 |
| " | 16 mm | 125 |
| " | 20 mm | 150 |
| " | 22 mm | 175 |
| 1" | 25 mm | 200 |
| " | 28 mm | 250 |
| " | 32 mm | 275 |
| " | 38 mm | 325 |
| " | 45 mm | 375 |
| 2" | 51 mm | 425 |
Comb binding is one of many ways to bind pages together into a book. This method uses round plastic spines with 19 rings or 21 rings 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. 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 up to . Spine lengths are generally 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.