Vulcan 203380OR Cobalt Drill Bit Set, 21-Piece, 1/16"-3/8""VULCAN" DRILL BIT SET 21 Piece. Made with a special alloy of M35 steel with 5 percent cobalt. Use on very hard or abrasive materials. All sizes 3 16" and larger have 3 flats on the shank so that the drill chuck gets a better grip on the drill bit. Sizes 7 16" and 1 2" have 3 8" reduced shank. 135 degree split point. Contains 1 each: 1 16", 5 64, 3 32, 7 64, 1 8, 9 64, 5 32, 11 64, 3 16, 13 64, 7 32, 15 64, 1 4, 17 64, 9 32, 19 64, 5 16, 21 64, 11 32,