Vulcan 492470OR PVB Cobalt Drill Bit Set, 17 PiecesMade of M35 steel, 5 percent cobalt, with extra thick drill core for rigidity and strength. Used in applications such as stainless steel and space age alloys. All sizes 3 16" and larger have 3 flats on the shank for a better grip on the drill bit. The 135 degree split point eliminates the need for a center punch and keeps the drill from skating on hard materials. Includes (1) one each: 5 64, 3 32, 7 64, 9 64, 5 32, 11 64, 3 16, 13 64, 7 32, 15 64, 1