Shimano RD-M8100 Deore XT Rear Derailleur Outer Plate Assembly Description: The Shimano RD-M8100 Deore XT Rear Derailleur Outer Plate Assembly is a factory replacement part. If a rear derailleur cage has become damaged but the rest of the derailleur can still be used, this part will help to restore the proper shifting performance of the rear derailleur. Features: Includes the outer derailleur cage plate and hardware, including a bumper for quieter operation, that ensures proper fitment within the derailleur body GS cage, otherwise known as a mid-length cage, will accept 12-speed cassettes with a 10-45T gear range Derailleur body, pulleys, inner cage, and other hardware sold separately See compatibility tab for full list of compatible derailleurs