DTH drill hammer 1.Fast drilling speed, low air consumption 2. Straightness and hole quality 3. High penetration rate DTH drill hammer With yeas ... experience, now Zhongrui can manufacturer the best quality DTH drill bit, DTH drill hammer and chisel bit, thread button bit. Now we ... can supply 90mm-254mm(3.5"-10") DTH drill bit, 340,350,360,380, COP44, COP54, COP64, COP84 , 3 ...