The common hole / punch pattern is 4:1 pitch (4 holes per 1") spiral binding; or sometimes referred to as 6mm. 4:1 means there are four holes per inch on the binding edge of the document. The holes / punch pattern for this style are usually either round or oval shaped. Elements for binding documents with 4:1 pitch spiral coil are available in sizes ranging from 6mm up to 50mm in diameter. Allowing binding documents that are up to two inches.