Countersink Drill Bit 22pc Set W/case Adjustable Depth Stop Collars Woodworking. Countersink pilot bits perfectly match the size of the wood screw Tapered Bit Set Tapered Drill Bit Countersink Drill Set Adjustable Stop Collar Carpentry Countersink Drill Bit Set 5-12# Woodworking Tools includes bits for drilling pilot holes for screw sizes 5#,6#,7# ,8#.9#,10# and 12# Twist screws on the same axis,and screw nut below the board plane, drill collars can adjust up and down! Apply to with a clamp or joint drilling machine,suitable for drilling in the hard wood and wood floor,machine screw for wood screw. Product Description Material:HSS Drill 4241 Black chamfer drill body material:Steel #45 Shank:Straight Shank 5#:1/8/3.18mm(The corresponding bit size),9.5mm(Chamfer size) 6#:9/64/3.58mm(The corresponding bit size),9.5mm(Chamfer size) 7#:5/32/3.97mm(The corresponding bit size),9.5mm(Chamfer size) 8#:11/64/4.37mm(The corresponding bit size),9.5mm(Chamfer size) 9#:3/16/4.76mm(The corresponding bit size),9.5mm(Chamfer size) 10#:13/64/5.15mm(The corresponding bit size),9.5mm(Chamfer size) 12#:7/32/5.56mm(The corresponding bit size),9.5mm(Chamfer size)