The Sram Red WiFLi Rear Derailleur has been designed for road cycling where you need faster shifting with less weight and greater acceleration, thanks to the exclusive WiFli technology. It is compatible with 28 and 32 tooth and 11 speeds. This bike rear derailleur is made of carbon and ceramic pulley bearing. It features Exact Actuation technology that favors precision, speed, and silent operation. It includes a new AeroGlide toothed pulley design that provides cushioning, less noise, and efficient driving.SRAM Rear Derailleur Red 2211-speed, Exact Actuationcarbon cage, titanium parallelogramm spring, AeroGlide pulleys with ceramic bearings and improved profile for lighter run, grey/blackmedium cage, max.32 teeth.For 2x10V systems.- Compatible with cassettes 11-42T.