Drill BitChina Roller Bit with Full Insert 12 1/4" IADC Code 637 Single Roller Bit Single Roller Cutter Roller Cones Bit Rotary Digging Rock Bit TCI, Find details about China Single Roller Bit, Roller Bit from Roller Bit with Full Insert 12 1/4" IADC Code 637 Single Roller Bit Single Roller Cutter Roller Cones Bit Rotary Digging Rock Bit TCI