Wire binding machines are available in two pitches, or punching patterns:
3:1 pitch Wire binding machines will punch 3 holes per inch with a binding capacity of 3/16"-9/16" (5-120 sheets of 20# paper) & use 32-loop binding wires (3:1 pitch).
2:1 pitch Wire binding machines will punch 2 holes per inch with a binding capacity of 5/8"-1-1/4" (110-250 sheets of 20# paper) & use 21-loop binding wires (2:1 pitch).