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. Product Details: Includes a chain gap tool that makes it easy to set up the correct chain length 14T lower pulley Type 3 clutch is smoother and more durable