The SRAM GX X-HORIZON rear derailleur is engineered for smooth, reliable shifting action-from the larger upper pulley offset to the 12-tooth X-SYNC pulley wheels. By eliminating unwanted chain movement, X-HORIZON(TM) shifts faster, puts an end to ghost shifting and reduces shift force and chain slap. And with CAGE LOCK(TM) technology, wheel removal and installation are easier than ever Features: X-HORIZON design reduces shift force, ghost shifting and cage slap 12-tooth X-SYNC pulley wheels Large upper pulley offset automatically adjusts chain gap Sealed cartridge bearings Aluminum cage