Comb binding (sometimes referred to as "cerlox or surelox binding") is one of many ways to bind pages together into a book. This method uses 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.
To bind a document, the user first punches holes in the paper with a specialized hole punch.
Then the user chooses a spine size that will match the document.
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.