... China for many years. Including of tapered button bit, retract button bit, thread button bit.With ISO certificate & quality control.Button bits with 6tips, 7tips, 8tips, we ... hex, 19mm, 22mm) Internal Drill rods(chisel bit integral rod. 19mm, 22mm; Shank hex. 19mm, 22mm) B. Thread Button BitThread button bit (33mm, 35mm, 45mm ...