water well drilling hammer 350,350,360,380 wind pressure:0.5-2.5mpa Impact frequency :25 ... supply 90mm-254mm(3.5"-10") DTH bit, 340,350,360,380, COP44, COP54, COP64, COP84 , 3"-8" DTH water well ... drilling hammer, 340,350,360,380 4",5",6",8" quick water well drilling hammer ... (at 1.7Mpa)15-34API(4 1/2)" REG195-254 360 water well drilling hammer