China 8 1/2" IADC Code 637 Rotary Digging Machine with Straight Shank Single Roller Cutter with Cone 1/2/3 Repalceable TCI Bit, Find details about China Single Roller Bit, Roller Bit from 8 1/2" IADC Code 637 Rotary Digging Machine with Straight Shank Single Roller Cutter with Cone 1/2/3 Repalceable TCI Bit