... -resistance.6.ZHY-600 series drill bit, grain size 0.4um, Co12%, HRC60, AlTiN coating, Kennametal material, for high speed cutting.7.ZHY ... -650 series drill bit, grain size 0.2um, Co9%, HRC65 ... ~68, AlTiN-S coating, Sandvik material, for high speed cutting.8 ...