Description: Five piece set includes bits for drilling pilot holes for screw sizes The applicable scope is suitable for workpiece under 25 HRC hardness, such as carbon steel, sheet iron, insulation board, PVC board, wood, etc. Adjustable counter sleeve depth with Allen wrench,drilling length can be adjusted for various length screws simply by loosening and tightening the setscrew The chamfering is five-edged, and in the course of the process, the sawdust can be discharged more quickly, and a smooth and smooth counterbore is drilled at one time to insert the screw cap into the surface of the workpiece. Standard hex shank is quick change compatible,drill and countersink for wood screws without changing bits. Specification: Material : Steel Color: Black Size: Approx. Countersink Drill Diameter: 3mm/0.12inch; 4mm/0.16inch; 5mm/0.20inch; 6mm/0.24inch Chamfering Drill Diameter: 15mm/0.59inch Package Includes: 4 pieces Countersink Drill 1 piece Chamfering Drill Note: Due to the difference in the measurement , pls allow an error of 1 to 3mm