Tricone Bits, PDC Bits, Drag Bits manufacturer / supplier in China, offering Factory Price IADC437 4.40 Inches 112mm Roller Cone Drill Bits Rock Well Drilling, Wholesale Tricone Rock Drill IADC435 12.25" (311.1mm) for Hard Formation in Stock, Factory Price TCI Drilling Bit IADC435 17.5 Inches (444.5mm) with Mud Circulation and so on.