Four piece set includes bits for drilling pilot holes for screw sizes #6,#8,#10 and #12.
Special designed steel counter sleeve countersinks or counter bores pilot hole.
Adjustable counter sleeve depth with Allen wrench.
Standard hex shank is quick change compatible.
Drill and countersink for wood screws without changing bits.Drilling length can be adjusted for various length screws simply by loosening and tightening the setscrew.