X-Horizon(TM) design reduces shift force, ghost shifting and chain slap 12-tooth X-SYNC(TM) pulley wheels Large upper pulley offset automatically adjusts chain gap Roller Bearing Clutch means derailleur bounce and chain slap are eliminated without sacrificing precision Sealed cartridge bearings Aluminum Cage GX 1X 11sp Long 1to1 BLK 265UPC/EAN/GTIN: 710845770203