SRAM Red WiFli Rear Derailleur - 11 Speed, Medium Cage, BlackTop of the line rear derailleur with generous use of carbon fiber and titanium for maximum performance at minimal weight. Carbon fiber and aluminum construction Ceramic bearing pulleys Titanium hardware Product Specifics Rear Derailleur Mount Type: 10x1 Standard Rear Der Shifter Compatibility: SRAM Exact Actuation Cage Length: Medium Drivetrain Speeds: 11 Weight: 152 Color: Black keyword search: RD4621 Chain Wrap Capacity (teeth): 37 Largest Cog: 32