Bordo Drill Set Reduced Shank 9/16-1 inch ½ 8 pce Imperial 2651-S2118 notched point 30 helix reduced shank drill. BRIGHT BLACK FINISH These drills are ground and then a black finish is achieved by steam tempering, a thermal process resulting in a porous tool coating. This surface aids chip flow and heat dissipation. The drill is then ground a second time to achieve a bright finish on the shank and cutting edges. 2651 9 16: 9 16" 1 2" Reduced Shank Drill 2651 5 8: 5 8" 1 2" Reduced Shank Drill 2651 11 16: 11 16" 1 2"