... Straightness and hole quality 3. High penetration rate DTH drill hammer With yeas of experience, now Zhongrui can manufacturer the best quality ... . Now we can supply 90mm-254mm(3.5"-10") DTH drill bit, 340,350,360,380, COP44, COP54, COP64, COP84 , ... 5",6",8" quick hammer with very good price and service. No.ModelOutside diameterLength (without bit)Weight (without bit)Working pressureImpact frequencyAir ...