A fret is a separator. On a roulette wheel the little tab that separates the numbers is called a fret. If you find a live roulette table with a loose or worn fret you should be able to figure out which numbers it will favor. This is one of those so called “wheel biases” that pros sometimes talk about. They are obviously found only on LIVE games, another reason the play live versus computer software games.
So don’t fret, they are a good thing!
A Malformed Separator Between Two Numbers = More Money in Your Pocket