SRAM NX Eagle Rear Derailleur - 12 Speed Long Cage BlackSRAM NX Eagle Rear Derailleur 12 Speed Long Cage Black. The NX Eagle rear derailleur features the proven SRAM 1x specific X HORIZON design. The larger 14 tooth X SYNC lower pulley easily facilitates 11 to 50 and 10 to 50 tooth cassette capacity and also adds to NX Eagles overall smooth pedaling feel. The Type 3 ROLLER BEARING CLUTCH provides quiet consistent performance and durability. Mounting system and re positioned Cage Lock offer greater