1/4-inch hex shank conical drill bit set, quick change with 1 small hex key for woodworking

1. Four HSS drill bits for drilling holes with screw sizes #6, #8, #10, and #12. 2. Specially designed steel sleeve countersinks for drilling or countersinking holes. Drill and countersink for wood screws without changing bits. 3. Adjustable countersleeve depth with hex key. The standard 6.35 mm hex shank is compatible with quick-change bits. 4. Drilling length can be adjusted for different screw lengths simply by loosening and tightening the adjustment screw. 5. Suitable for drilling materials with a hardness below 25 HRC, such as carbon steel, sheet metal, insulation board, PVC sheet, wood board, etc. For use on a drill with a chuck or connector.