... of experience, now Zhongrui can manufacturer the best quality DTH drill bit, DTH hammer and chisel bit, thread button bit. Now we ... can supply 90mm-254mm(3.5"-10") DTH hammer, 340,350,360,380, COP44, COP54, COP64, COP84 , 3 ... "-8" DTH hammer, 340,350,360,380 4",5",6",8" quick ... (at 1.7Mpa)15-34API(4 1/2)" REG195-254 DTH drilling hammer