... -203mm bit Good quality, low price Down hole rock roller bit With yeas of experience, now Zhongrui ... can manufacturer the best quality DTH rock drill bits, DTH hammer and chisel bit, thread ... can supply 90mm-254mm(3.5"-10") DTH rock drill bits, 340,350,360,380, COP44, COP54, COP64, COP84 , ... 3"-8" DTH hammer, 340,350,360,380 4",5",6",8" quick hammer with very good ...