Greenlee Drill & Tap bits. Combination Drill/Tap and Countersink Set, Pieces 6, Material High Speed Steel, Drill Style Twist, Tap Sizes #6-32, 8-32, 10-24, 10-32, 12-24, 1/4-20, Plug Tap Style, 1/4 Inch Hex Shank, Back Taper Beyond Tap, Deburr/Countersink Beyond Back Taper, Split Point Drill Tip, Tap Up To 10 Gauge Mild Steel, Aluminum, Copper, Brass, Includes Plastic Case. I bought a set of these a couple of months ago. I build and repair a lot of control cabinets for the equipment I work on. These bits are great. They will drill the hole, thread it and debur it all in one shot. Best used with adjustable clutch drills to prevent stripping threads when cutting. I have used all 6 sizes in the set for no less that 30 holes each some a lot more. I highly recommend them. I bought mine at a local electrical supply house for $24.95 Grainger has the best ONLINE price that I have seen at $29.95. Check your local suppliers first.