SRAM NX X-Horizon 11-Speed Rear DerailleurThe SRAM NX X HORIZON rear derailleur provides the same smooth, reliable shifting action as XX1 from the larger upper pulley offset to the 12 tooth X SYNC pulley wheels. By eliminating unwanted chain movement, X HORIZON shifts faster, puts an end to ghost shifting and reduces shift force and chain slap. And with CAGE LOCK technology, wheel removal and installation are easier than ever.