Drill America D/ACO29/32 29/32" Reduced Shank Cobalt Drill Bit, 1/2" Shank, Drill America, D/ACO29/32Drill America D ACO29 32 29 32" Reduced Shank Cobalt Drill Bit, 1 2" Shank, Drill America, D ACO29 32 Cobalt reduced shank drills are heavy Duty 135 Split Point, Cobalt Steel, Jobber Length, manufactured to National Aerospace standard 907. These drill bits display high red hardness, permitting speeds up to 30% greater than with conventional M2 high speed steel, and are especially effective in drilling tough, high tensile strength materials like