One of our greatest inventions! The easiest and gentlest way to enlarge finger holes on new grips (these are specifically for DOWEL grips. You DON'T need this item for beginner grips or 3Guards). Don't use knives or cut your grips! These files last for ages so when you buy one, stash it in your junk drawer because it will work for many years on all your future grips. The small file works on grip sizes 000 - 2, and the large file is for sizes 3 - 4. Remember, we make these files to make it easy on you! Buying one isn't really necessary... You can simply wrap a pencil with sandpaper and use that to file your finger holes!