#6 wood countersink, tapered drill, widened flutes for drilling fast, clean pilot holes, 4 cutter, adjustable counter bore cuts & clears chips for fast, smooth countsinking, counter bore attaches securely to the flats on shank with hex screws & adjusts for controlled pilot hole depth, 1/4″ quick change shank reduces slipping in standard chucks, compatible with all 1/4″ quick change chucks including impact drills, use for fine woodworking projects, bit diameter 9/64″, counter bore size 5/16″, plug size 5/16″, shank size 1/4″.