1、Excellent Cutting Power: Countersink drill bit set has excellent cutting power, high durability and good wear resistance 2、Faster Operation: The drill bit can be accurately inserted into the countersunk socket, and the two chamfered grooves enable faster operation and self cleaning drilling on chips 3、For Various Materials: Countersink drill bits are ideal for bench drills, hand drills and traditional electric drills, which are very suitable for wood, fiberboard, particleboard, plywood, plastic, PVC, rubber, etc. 4、High Hardness And Good Wear Resistance: The drill bit is made of high grade steel, and the countersunk drill socket is made of high carbon steel, which has high hardness and good wear resistance 5、1/4in Hex Shank Diameter: The diameter of the hex shank of the drill socket is 1/4in, and the tool diameter includes 3.5, 3.25, 2.75, 2.5, 2mm(9/64, 1/8, 7/64, 3/32, 5/64in)