Engineering & Construction Machinery PartsChina 12 1/4" IADC Code 637 Roller Bit with Cone 1/2/3 Single Roller Cutter with Basis Replaceable Drill Bit, Find details about China Single Roller Bit, Roller Bit from 12 1/4" IADC Code 637 Roller Bit with Cone 1/2/3 Single Roller Cutter with Basis Replaceable Drill Bit