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