KING DO WAY 4pcs HSS 5 Flute Countersink Drill Bit Set Reamer Woodworking Chamfer 3mm-6mm Four piece set includes bits for drilling pilot holes for screw sizes 3mm, 4mm, 5mm, 6mm. Special designed steel counter sleeve countersinks or counter bores pilot hole. Adjustable counter sleeve depth with wrench. Drilling length can be adjusted for various length screws simply by loosening and tightening the setscrew. Chamfer is 5 flutes,In the process of using, can discharge the wood more rapid, sink hole disposable drilled smooth, screw cap perfect embedded in the surface of workpiece.