Engineering & Construction Machinery PartsChina 12 1/4" (311.1mm) IADC637G Tricone Drill Bit, Tricone Rock Bit, TCI Tricone Bit, Find details about China Tricone Drill Bit, Rock Bit from 12 1/4" (311.1mm) IADC637G Tricone Drill Bit, Tricone Rock Bit, TCI Tricone Bit