... -HRC60~68, Co9%~12% -High aluminum coating drill bit -For high speed cutting 2 Flute High Speed ... 2 flutes high speed drill bit, high speed 2 flutes short flute drill bit with cooled(3xd), 2 Flute ... High Speed Tungsten Carbide Drill Bit With Cooled(5xd).2 ... Co, the better wear-resistance.6.ZHY-600 series drill bit, grain size 0.4um, Co12%, HRC60, ...