The SRAM X0 10 Speed Rear Derailleur - Type 2.1 now features an internal change to the clutch mechanism which improves performance and longevity compared to the previous Type 2. This rear mech uses exact actuation which allows for precise and dependable shifting performance along with a focused chassis design for all conditions and usage. Cage Lock technology allows wheel removal and installation along with chain installation to become faster and simpler. The roller bearing clutch delivers maximum drivetrain stability even on the most punishing terrain, eliminating derailleur bounce and chain slap without sacrificing precision. Sram X0 Type 2.1 Rear Derailleur Features 10 Speed Type 2.1 clutch mechanism  Available in Black/Red, Black or Silver in Long, Medium or Short cage designs.