Product Usage ---Suitable for drilling workpieces with hardness less than 25 HRC, such as carbon steel, iron sheets, insulation plates, PVC plates, wood panels, etc. . Drill with chuck or connector. Product set ---4 HSS pieces built to drill holes with screws sizes #6, #8, #10 and #12. How to use---The drill length can be adjusted for different screw lengths by loosening and tightening the grub screw. Adjustable depth ---Adjustable counter sleeve depth with wrench. Compatible with standard 1/4" shank. Steel Plywood ---Specially designed steel plywood for counterfeit holes or holes. Drill and countersink for wood screws without changing bits Features: Condition: New. Material: 4241 high speed steel. Color: as picture shown. Drill Size: #6, #8, #10, #12. #6: 2.38mm. #8: 2.78mm. 10#: 3.175mm. 12#: 3.56mm.