Irwin 10231CB IRWIN Unibit Cobalt Step Drill Bit, No.1 (10231CB)

10231CB Unibit® Cobalt High Speed Steel Fractional No.1 Step Drill - 13 Steps. 6X Longer life vs. the competition. Engineered with M35 Cobalt steel for maximum life when drilling in tough stee. Radial concave flute. Laser marked sizes. Description: No.1. Hole Sizes: 1/8" - 1/2" (1/32" Increments). No. of Holes: 13 steps. Hex Shank Size: 1/4".