Since this is a carbide blade counter sink, it is suitable for hardened steel and so on. It works better with relatively slow cutting speed (10-20 m/min). For high-hardness steel and over 240 HB. Number of blades: 3. Tip diameter: 0.06 inches (1.5 mm). Effective blade diameter: 0.2 inches (6.3 mm). Total length: 1.8 inches (45 mm). 0.2 in (5 mm) Cutter Tip Corner (°): 90 3 Blade Tip Angle: 90 ° Non-Coated For Drilling Machines Carbide (K20)