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.