... special formations thread button bitsThread button bits made with high quality of best quality alloy steel bar and tungsten carbides, through heat ... face design: Flat face, drop centre, Normal and Retrac body.Tungsten carbide (Buttons): Spherical, ballistic and Conical. (Threaded R32, R38, ... T38, T45, T51, bit diameter: 45mm-127mm);(2) Main button bits diameters:R32-45mm, R32-51, R32-64, R32-76 ...