21 piece, black oxide, metal, drill bit set, set consists of: (2) 1/16", (2) 5/64", 3/32", 7/64", (2) 1/8", 9/64", 5/32", 11/64", (2) 3/16", 13/64", (1) 7/32", 15/64", (2) 1/4", 5/16", 3/8" & 1/2" drill bits, no skate tip for clean & accurate starts, black oxide coating generates less friction, three-flat shank promotes better grip on bits 3/16" & larger, universal drilling applications designed for general purpose use, high visibility marking provide clearly marked diameter.