8pcs Wood Countersink Drill Bit Set with 4pcs Standard Countersinks and 4pcs Four Flute Chamfer Cutters, can be used with bench drill, hand drill or other professional drilling machine. To avoid slippage or eccentricity during drilling, we recommend using a bench drill or fixing the drill. 7pcs Countersink Drill Bit Set made of high quality carbon steel with titanium coating. The drilling length can be adjusted for different screw lengths. The chamfer is composed of 5 flutes, which can discharge the wood faster when using. 6pcs 1/4" 90 Degree 5 Flute Hex Shank Drill Bit Set, made of standard high speed steel. Through high frequency quenching for heat treatment, the HSS countersinks have high hardness and toughness. With titanium coating, the chamfer kit is rust-proof and has a long service life. 3pcs step cone drill bits set forged from high speed steel coated with titanium. The hexagonal shank of the step drill bits adopts groove design, helps the electric drill to fix it more