SizeRAM XX1 Rear Derailleur - 11 Sizepeed, Medium Cage, Black/Red

Wide-tooth, narrow-tooth pulley wheel maximizes chain control by fitting inner and outer chain links perfectly X-Horizon design maintains constant chain gap across all gears and eliminates ghost shifting Roller bearing clutch eliminates derailleur bounce and chain slap Cage Lock feature simplifies wheel removal and chain installation Must be used with SRAM 1x11 shifter and cassette