Bordo Drill Set Reduced Shank 5/8-1 inch ½ 4 pce Imperial 2651-S1118 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 5 8: 5 8" 1 2" Reduced Shank Drill 2651 3 4: 3 4" 1 2" Reduced Shank Drill 2651 7 8: 7 8" 1 2"