Greenlee Combination Drill/Tap Bits complete hole drilling, tapping, deburring/countersinking in one operation with power drill saves time. They are back tapered beyond tap to prevent thread damage from over-drilling. Deburr/countersink is also provided on bit beyond back taper. They are made from hardened high-speed steel vs. carbon steel for longer life. They have a high quality hex shank to ensure strong connection to drill chuck. Designed to tap up to 10 gauge metal. Quick change adapter included in both metric and standard kits.