#10 Wood Countersink, Tapered Drill Features 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 The 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 3/16", Counter Bore Size 7/16", Plug Size 7/16", Shank Size 1/4".