... China for many years. Including of tapered button bit, retract button bit, thread button bit. With ISO certificate & quality control. Button bits ... can manufacture the following types: A. Taper button bitTapered button bit(28mm, 30mm, 32mm, 33mm, 34mm, 36mm, 38mm, 40mm, 42mm, ... 19mm, 22mm, 25mm; Shank hex, 19mm, 22mm) Internal Drill rods(chisel bit integral rod. 19mm, 22mm; Shank hex. 19mm, 22mm) B. ...