high pressure down-hole roller bit water hole:two match hammer:3-8inch 90-203mm ... , thread button bit. Now we can supply 90mm-254mm(3.5"-10") DTH rock drill bits, 340,350,360,380, COP44 ... , COP84 , 3"-8" DTH hammer, 340,350,360,380 4",5",6",8" quick hammer with very good price and service ... . of pilot bitMatch hammerWeight(kg)183mm163mm188mm140mm160mmZRC130G60.3 Down hole rock roller bit