... rock, hard rock and any other special formations thread button bitsThread button bits made with high quality of best quality alloy steel ... , R38, T38, T45, T51, bit diameter: 45mm-127mm);(2) Main button bits diameters:R32-45mm, R32-51, R32-64, R32-76 ... as client's requirement.(4)Productivity: 10000pcs/ month MAXDRILL drill button bits