... hole quality 3. High penetration rate DTH drill hammer With yeas of experience, now Zhongrui can manufacturer ... the best quality DTH drill bit, DTH drill hammer and ... we can supply 90mm-254mm(3.5"-10") DTH drill bit, 340,350,360,380, COP44, COP54, COP64 ... 360,380 4",5",6",8" quick hammer with very good price and service. No.ModelOutside ...