ITEM NAME:4pcs HSS Countersink Drill Bit Set + Quick Change Hex Shank Screw JR 4 Pcs set includes bits for drilling pilot holes for screw sizes #6,#8,#10,#12. Function: can drill the screw holes and keep on the same axis,after screw in screwï ¼Å’nut below the board! Apply to with a clamp or joint drilling machine, suitable for drilling in the hard wood and wood floor, machine screw for wood screw. Specification: Material: HSS Drill 4241 Black chamfer drill body material: steel 45 Dimension: model the corresponding bit size #6 2.38mm #8 2.78mm #10 3.175mm #12 3.56mm Shank:6.35mm dia hex shank. Package include 4 x Drill Bits 1 x Hex Shank 4 Pcs set includes bits for drilling pilot holes for screw sizes #6,#8,#10,#12. Function: can drill the screw holes and keep on the same axis,after screw in screwï ¼Å’nut below the board! Apply to with a clamp or joint drilling machine, suitable for drilling in the hard wood and wood floor, machine screw for wood screw. Specification: Material: HSS Drill 4241 Black chamfer drill body material: steel 45 Dimension: model the corresponding bit size #6 2.38mm #8 2.78mm #10 3.175mm #12 3.56mm Shank:6.35mm dia hex shank. Package include 4 x Drill Bits 1 x Hex Shank.Black chamfer drill body material: steel 45. Material: HSS Drill 4241. Shank:6.35mm dia hex shank. 1 x Hex Shank. Apply to with a clamp or joint drilling machine, suitable for drilling in the hard wood and wood floor, machine screw for wood screw.