China 8 1/2 Inch IADC437/537/637 Carbide TCI Tricone Roller Cone Bit/Drill Bit for Water Well Drilling, Find details about China Tungsten Carbide Insert Bits, Rubber Sealed Jounal Bearing from 8 1/2 Inch IADC437/537/637 Carbide TCI Tricone Roller Cone Bit/Drill Bit for Water Well Drilling