BLACK AND GOLD ULTRA BOR SUPER PREMIUM MECHANICS LENGTH 21 PIECE SET IN METAL INDEX. 135 DEGREE SPLIT POINT. SIZES 1/16 - 3/8 BY 64THS. 3 FLATS ON SHANK 3/16 AND LARGERBODY AND CLEARANCE ARE GOLD SURFACE TREATED FOR MAXIMUM LUBRICITY. ESPECIALLY DESIGNED FOR HAND HELD DRILLS. RECOMMENDED FOR USE IN WORK HARDENING GRADES OF STAINLESS STEEL AND OTHER HARD METAL DRILLING APPLICATIONS.