Irwin Wood Countersinks #14 15/64 In.Tapered drill with widened flutes for drilling fast, clean pilot holes. Adjustable four cutter counterbore cuts and clears chips quicker for fast, smooth countersinking. Counterbore attaches to flats on shank with two hex screws for a secure fit, and can be adjusted for controlled pilot hole depth. 1 4" quick change shank reduces slipping in standard chucks and is compatible with all 1 4" quick change chucks, including impact drills.