PDC Drill Bits, Tricone Bits, DTH Hammer manufacturer / supplier in China, offering 8 1/2inch 215.9mm API Standard Mill Tooth Steel Tooth Tricone Bits, 12 1/4′ ′ IADC437 Oil for Hard Rock Tricone Rock Bits, 17 1/2" IADC535 API Standard Mill Tooth Steel Tooth Tricone Bits and so on.