Carbide Tipped Adjustable Countersinks (for wood screws) are designed to cut a bevel in wood or plastic for wood screw heads ranging from #4 to #10. They attach to a drill with two set screws and can be adjusted up and down the drill for any length from a #4 to a #10 wood screw. For use with 3/32 to 3/16 diameter drills.
Adjustable Countersink page 172A
adjustable countersink