SRAM Red WiFli Rear Derailleur - 10 Speed Medium Cage Black/SilverSRAM Red WiFli Rear Derailleur 10 Speed Medium Cage Black Silver. Top 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 Compatible with other SRAM 10 speed drive train components TECH SPECS Rear Derailleur Mount Type 10x1 Standard Rear Der Shifter Compatibility SRAM Exact Actuation Cage Length Medium