SRAM XX1 Eagle Rear Derailleur - 12-Speed Long Cage 52t Max LunarOccupying its rightful place at the top of the Eagle ecosystem the XX1 Eagle rear derailleur gives no compromise racers and dream bike builders a true top tier option. The crisp precise XX1 shifting feel athletes rely on features an updated cage geometry for improved chain management. Type 3 clutch is smoother and more durable 14T lower pulley Includes a chain gap tool that makes it easy to set up the correct chain length Rear Derailleur Mount Type