China Thread R25/R28/R32/R38/T38/T45/T51/Gt60/EL60/EL68/St58/St68/ED68 Top Hammer Hole Threaded Drill/Button Bit for Drifting and Tunnelling, Find details about China Top Hammer Drill Bit, Top Hammer Drill Bit Thread from Thread R25/R28/R32/R38/T38/T45/T51/Gt60/EL60/EL68/St58/St68/ED68 Top Hammer Hole Threaded Drill/Button Bit for Drifting and Tunnelling