TheSram XX1 11 Speed Rear Derailleurfeatures a unique horizontal design to create a derailleur that offers constant fast, precise shifts even under excessive amounts of stress! This design has been entitled the "horizontal parallelogram" which in essence means that the SRAM XX1 Rear Derailleur keeps a constant chain gap across all 11 gears, for an overall much more reliable shifting action that removes ghost shifting while providing a faster action than previous versions! TheSRAM XX1is made for the super bumpy trails, with a fantastically sturdy build that also helps reduce chain bounce and slapping you can be sure that even on the trickiest of rides thederailleurwill back you up with unmatched shifting performance! Another fantastic feature of the Sram XX1 11 Speed Rear Derailleur is the Cage Lock technology, this essentially makes it very easy in both wheel removal and installation, meaning you can get onto riding much quicker with less hassle! Sram XX1 11 Speed Rear Derailleur Features Large upper pulley offset automatically adjusts chain gap X-Horizon design reduces shift force and ghost shifting 12-tooth X-Sync pulley wheels Type 2 Technologies: Roller Bearing Clutch™and Cage Lock™ New silent pulley tooth design Sram XX1 11 Speed Rear Derailleur Specifications Weight: 220 grams Compatibility: X-Actuation, XX1 11 Speed Pulleys: 12T X-SYNC pulley wheels Technology Highlights: X-Actuation, X-Horizon, Roller Bearing Clutch, Cage Lock