1/4 Hex Shank Drill Bit Set. The 4-piece set includes a bit set for drilling pilot holes for screw sizes 6, 10, 13, and 16. Function: Can drill screw holes and stay on the same axis, after screw the nut under the board Specially designed steel plywood for the guide holes. The drill length can be adjusted for different screw lengths simply by loosening and tightening the grub screw. Material: High Speed Steel Christmas Gift for Dad/Father, Husband, Boyfriend, Men, DIYer. Apply with collet or joint drill machine, suitable for drilling in hardwood and wooden floor, wood screw machine screw. Features: Size (the corresponding size) : 6: 3mm. 10: 3.5mm. 13: 4mm. 16: 4.5mm. Shank: 1/4 hex shank Features: High quality product, sharp and durable. 4 piece set includes drill bits for drilling pilot holes for the screws of sizes 6, 10, 13, 16, with a mini hex key. It can drill the screw holes and stay on the same axis, after screwing the screw, nut under the board. Apply with pliers or joint drill machine, suitable for drilling in hardwoods and wooden floors, machine screw for wood screws. Function: can drill the screw holes and remain on the same axis, after screwing the nut under the board. Note: The color may differ slightly due to the lighting or brightness of your screen. Due to hand measurement, the sizes shown may vary by 0-3mm which is completely normal. Keep out of reach of children. The color of the actual item may vary from that photo o, depending on your computer''s display and brightness settings. Thank you Contents: 4 drill bits. 1 hexagonal rod