China 12 1/4" IADC Code 637 Single Roller Cutter with Basis Roller Cones Bit TCI Bit Replaceable Rock Drilling Tools, Find details about China Single Roller Bit, Roller Bit from 12 1/4" IADC Code 637 Single Roller Cutter with Basis Roller Cones Bit TCI Bit Replaceable Rock Drilling Tools