Use this special spiral coil to bind your large sized documents with spiral coil. It is designed for a 2.5 to 1 pitch hole pattern (or 0.400 hole spacing). It is used with a 2:1 wire binding hole pattern for binding large sized books with coil. This special type of coil is only available in sizes greater than 20mm and it utilizes a more ridgid filament to make the inserting process easier. The more rigid filament combined with the fact that there are less holes to insert your spiral coil through make this an ideal solution for large sized books. In fact, this special coil is even available in sizes as large as 56mm allowing you to bind books up to 2-1/4" thick. In the past, binding large documents with coil was a huge pain but using this coil it should be a whole lot easier. Or, if you don't have a 2:1 pitch punch we also carry 4:1 Pitch Spiral Coil, 3:1 Pitch Spiral Coil and 5:1 Pitch Spiral Coil.