5-piece countersink set for screw sizes #4, #6, #8, #10, and #12. Drill the correct pilot hole and recess for countersinking a screw all in one step. Adjustable four-cutter counterbore for fast, smooth cuts in all types of wood and plastic. Loosen to adjust the depth for variable length screws. Drills tapered to match the profile of traditional woodworking screws.