Set of 4 fret polishing rubbers.150-180-400-1000 grit.Easy and fast fret polishing tool. Erasing the small scratches of the fret polishing or cleaning dirty frets. Because of this softness, rubber fits to fret arch perfectly. Also soft rubber keeps the fingerboard damage to a minimum. Easy to cut this rubber by cutter knife for your fret work. This is a great rust remover and polisher!