high pressure down-hole roller bit water hole:two match hammer:3-8inch 90-203mm bit Good quality, low price With yeas of experience, now ... ,360,380, COP44, COP54, COP64, COP84 , 3"-8" DTH hammer, 340,350,360,380 4",5",6",8" quick hammer with very ... . of ring bitOuter dia. of pilot bitMatch hammerWeight(kg)183mm163mm188mm140mm160mmZRC130G60.3 Down hole rock roller bit