Wire Binding Supplies are also known as Twin Loop, Double-O, or Wire-O. All use the same binding method: a double strand of wire, shaped like an open circle, that gets inserted into a punched hole and has to be crimped closed and then binds the pages.
An 11" binding edge of paper uses
32 holes to bind with the 3:1 pitch
and 21 holes on the 2:1 pitch.