PDC Drill Bits, Tricone Bits, DTH Hammer manufacturer / supplier in China, offering 6 3/4 Inch 171mm IADC 537 Three Roller Bit Tricone Drill Bit, 7 1/2′ ′ Inch IADC 537 Borehole Drilling Bit Tricone Drill Bit, 4 1/2 Inch Medium Hard Rock Drilling Tungsten Carbide Insert Bit for Well Drilling and so on.