Greenlee DTAP12-24 Combination Drill and Tap Bit, 12-24NC Complete hole drilling, tapping, deburring and countersinking in one operation with power drill saves labor and time Back tapered beyond tap to prevent thread damage from over-drilling Deburr/countersink also provided on bit beyond back taper Made from hardened high-speed steel vs carbon steel for longer life Designed to tap up to 10-gauge metal