ITEM NAME:4pcs HSS Countersink Drill Bit Set + Quick Change Hex Shank Screw txT sqTEUS 4 Pcs set includes bits for drilling pilot holes for screw sizes #6,#8,#10,#12..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.