-Micro Grain 0.2um/0.4um -Helix Angle 35 degree -HRC60~68, Co9%~12% -High aluminum coating drill bit -For high speed cutting 2 ... three types: Standard 2 flutes high speed drill bit, high speed 2 flutes short flute drill bit with cooled(3xd), 2 Flute High Speed ... higher Co, the better wear-resistance.6.ZHY-600 series drill bit, grain size 0.4um, Co12%, HRC60, AlTiN coating, Kennametal material ...