Description The standard 4:1. Pitch refers to the holes-per-inch or the hole spacing. It is reflected in a ratio that includes the number of holes, a punctuation colon, and then the inch measurement. For example, 4:1. This ratio is read aloud/pronounced as “four to one” and means four holes for every 1 inch of length. 4:1 pitch binding coil spines are by far the most popular.
