... three types: Standard 2 flutes high speed drill bit, high speed 2 flutes short flute drill bit with cooled(3xd), 2 Flute High ... higher Co, the better wear-resistance.6.ZHY-600 series drill bit, grain size 0.4um, Co12%, HRC60, AlTiN coating, Kennametal ... carbide inserts, collet, chuck, tool holder, tool heads, carbide rod, reamer, nut, spanner, etc. ZHY 2 Flute High Speed Tungsten Carbide Drill Bit