Evolution Cyclone Premium Grade Cutters. Made of M2AL high speed steel, with optimized teeth hardness and heat treated to 68HRC to maximize cutter performance. Also features a tapered hardness from the shank, through the cutter body and to the cutter teeth. Making the cutter more resistant to the torque created while cutting and thus preventing breakage. Evolution standard geometry is sufficient for most drilling applications. Cutters are manufactured to maximize hole accuracy, while minimizing cutter vibration and extending cutter life. Cutter comes with a pilot pin. The pilot pin is provided to ensure coolant is delivered directly to the cutting surface, to allow for automatic slug ejection, and to assist with hole drilling accuracy. 3/4"shank with 2 flats.