Every detail of the 11-speed X1 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™ 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 everLarge upper pulley offset automatically adjusts chain gap,X-HORIZON™ design reduces shift force, ghost shifting and chain slap,12-tooth X-SYNC™ pulley wheels,Aluminum Cage,Sealed cartridge bearings.