Rear Derailleur Sram X01 Eagle B2 12sp - LunarRear Derailleur Sram X01 Eagle B2 12sp Lunar Elevating the shift, expanding the capable, the X01 Eagle derailleur features an updated cage architecture, to provide better chain management than ever. The X01 Eagle rear derailleur works with the new 10 52t cassettes and is backwards compatible to also work with 10 50t options. As part of the new Eagle Colorsystem, it comes in X01 Eagle signature colorway to go perfectly with any color cassette and chain