Diamond Countersink 3/8" X 1/4"-28; 100 deg., .159" (#21) integrated pilot; 40/50-diamond

Diamond Countersink 3/8" X 1/4"-28; 100 degree with .159" (#21) integrated pilot; 40/50 grit diamond. Ideal for use on carbon fiber, fiberglass, fiber reinforced plastics and other abrasive type materials