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