Sram XX1 Type 2. 1 11 Speed Rear Derailleur Never settling, Sram continues to refine their 1X drivetrain components. The newest incarnation of the Sram XX1 Type 2. 1 11 Speed derailleur includes some minor tweaks that dial in the system just a hair more, inching it closer to the edge of perfection. A new silent 12T X-Synch pulley tooth design reduces noise, engages the chain quicker, and works in conjunction with the front chaining for superior chain retention. Cage Lock is another 2. 1 technology. No more wrestling with a rear derailleur during a trailside flat repair. Simply swing the cage forward, creating a slack chain, then lock it in place. The rear wheel now has unobstructed access to the dropouts. The Roller Bearing Clutch prevents the chainstay from looking like a chewed up pencil by practically eliminating chain slap and derailleur bounce. This also gives the drive train incredible stability through even in the most grueling terrain. XX1 Type 2. 1 rear derailleurs continue to utilize the proven X-Horizon horizontal parallelogram and pulley offset design. Together these limit cage movement to a side-to-side motion, and not an up-and-down one and maintain a consistent chain gap to the cassette. This exercises the dreaded ghost shift, banishing it to poor-shifting purgatory, never to be seen again. The Sram XX1 Type 2. 1 11 speed rear derailleur is only compatible with the XX1 shifter and cassette. Features: Large upper pulley offset automatically adjusts chain gap X-Horizon design reduces shift force and ghost shifting Roller Bearing Clutch eliminates chain slap and derailleur bounce Cage Lock for easy wheel removal New silent pulley tooth design X-Actuation keeps shifting sharp and consistent 12-tooth X-Synch pulley wheels offer quicker chain engagement Specifications: Color: Black Speeds: 11 Speed Weight: 220g Compatibility: X-Actuation, XX1 11 Speed | Sram | Xx1 Type 2. 1 11Sp Rear Derailleur Black/ | Grey | 11 Speed, X-Actuation