We use 'em every day around here and they are handy as the dickens.

The flexible padded core keeps from scratching up stuff like little files do. It is a good idea tp put a piece of masking tape on both sides of a fret that you are going to work on.

Polishing the sharp edges from fret ends is easier than you think.... and certainly worth doing.

Magically Reduces Belly Fat! (No, it don't, but that sure sounded inviting on that commercial I just saw on the telly.