China Single Roller Cutter with Cone 1/2/3 8 1/2" IADC Code 637 Drill Bit Roller Cones Bit with Basis Replaceable, Find details about China Single Roller Bit, Roller Bit from Single Roller Cutter with Cone 1/2/3 8 1/2" IADC Code 637 Drill Bit Roller Cones Bit with Basis Replaceable