China 12 1/4" IADC Code 637 Single Roller Bit with Cone 1/2/3 Single Roller Cutter Roller Cones Bit Replaceable Drill Bit, Find details about China Single Roller Bit, Roller Bit from 12 1/4" IADC Code 637 Single Roller Bit with Cone 1/2/3 Single Roller Cutter Roller Cones Bit Replaceable Drill Bit