China Single Roller Cutter 8 1/2" IADC Code 637 Roller Cones Bit TCI Rock Drilling Tools Drill Bit Single Roller Bit, Find details about China Single Roller Bit, Roller Bit from Single Roller Cutter 8 1/2" IADC Code 637 Roller Cones Bit TCI Rock Drilling Tools Drill Bit Single Roller Bit