Shimano Ultegra RD-R8050 Rear Derailleur Bracket Axle Unit Description: The Shimano Ultegra RD-R8050 Rear Derailleur Bracket Axle Unit is a factory replacement part that connects the rear derailleur to a bicycle's derailleur hanger. If the stock bracket axle kit has become damaged, this replacement part will help to properly align the body of the rear derailleur for optimal shifting performance. Features: Includes the bracket, the bolt that goes into the derailleur hanger, and the B-Axle bolt that attaches the bracket to the rear derailleur body