1.Five piece set includes bits for drilling pilot holes for screw sizes #5,#6,#8,#10 and #12.
2.Special designed steel counter sleeve countersinks or counter bores pilot hole.
3.Adjustable counter sleeve depth with a wrench.
4.Drill and countersink can be used for wood and plastic without changing bits
5.Drilling length can be adjusted for various length screws simply by loosening and tightening the setscrew,Countersink or counter bore clean, smooth holes for screws and fasteners