Drilling tools manufacturer / supplier in China, offering 7 7/8 Inch 200mm IADC537 for Water Drilling Bit Tricone Cone Bit, 13 5/8 Inch IADC 637 for Water Drilling Well Tricone Roller Cone Bit, 13 5/8 Inch IADC 437 617 637 Drilling Watter Tricone Drill Bit and so on.