Carbide Tipped and made for use in drilling hardened steel in the range of 48 to 65 Rockwell "C" Holes may be drilled without annealing or appreciably changing the structure of the material Bonus 3 pack of 1/8" Double End Drill Bits KnKut 1/8" Double End Bits are surface treated for maximum lubricity KnKut 1/8" Double End Bits feature a 135-degree split point that will not walkThis drill bit can be used for drilling broken studs, spring bolts, die sections, broken easy outs, extra tough metals, exotic metals, brake drums, etc. NOTE: Heavy Pressure and low R.P.M."s recommended. Cutting oil should be used. Recommended for use in drill presses, but can be used in portable drills. SET INCLUDES: 1 piece each: 1/8", 3/16", 1/4", 5/16" x 4", 3/8" x 4" KnKut Double End Sheeter Drill Bits are excellent for thin gauge metals such as sheet metal. Made of hi-molybdenum tool steel and surface treated for maximum lubricity, our sheeter drills feature a 135-degree split point that will not walk.