29 Piece Cobalt Quick Change Hex Shank Drill Bit Set. 29 Piece Drill Bit Set contains sizes 1/16″ – 1/2″ by 1/64 COHEX Quick Change Drill Bits are designed for use in hand held and impact drills. Cobalt drill bits are are effective in drilling tough, high tensile strength materials. Display high red hardness, permitting speeds up to 30% greater than with conventional M2 high speed. These drill bits have a 135° split point tip fast penetration and accurate drilling and a 1/4 Hex Shank that can be used in quick change impact drivers. The length between the chucking slot on the shank to the end of the shank is standard 3/8″29 Piece Drill Bit Set contains sizes 1/16″ – 1/2″ by 1/64″ COHEX Quick Change Drill Bits are designed for use in hand held and impact drills. The length between the chucking slot on the shank to the end of the shank is standard 3/8.