Drill diameter: 0.3-1.2mm, shank diameter: approx. 1/8: 3.175mm. Tungsten carbide spiral tip drill bits with cutting edge, reduce cutting pressure and prevent bit from breaking, improve drilling accuracy. Ideal for circuit boards, plastics, fiberglass, wood, soft metals, etc. Carbide rods and tungsten steel rods, with high hardness, high resistance to wear, high strength, resistance to bending, anti-tampering and long tool life. Total length 38 mm. Package Contents: 10 pcb carbide drill bits with protective case.