... , T51-102MM, T51-127 etc. Button bit 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 ... . Used with soft, medium, hard rock formation. . Retarc Thread Button Bit