Cutting Hardness: HRC67-70, Drill Bit Diameter: 4.9mm / 0.19-inch, Flute Length: 50mm / 1.97-inch, Shank Diameter: 4.9mm / 0.19-inch, Total Length: 85mm / 3.35-inch; 2 x M42 High Speed Steel Twist Drill Bit M42 steel is high cobalt high-speed steel.