If you want for the fastest, quietest shifting around, look no further. The new SRAM RED Rear Derailleur has been designed to deliver the performance advantage youve come to expect from SRAM. The derailleur is designed with our Exact Actuation technology for precise, efficient shifting.Weve paid rapt attention to the finer details, like adding a hollow titanium anchor bolt and even refining tooth geometry of the jockey wheel. The result is that the chain runs through the new RED Rear Derailleur smoother and quieter than ever before. Exact Actuation shifting provides fast, accurate shifts. More clearance with 28t cassettes thanks to longer B knuckle. New silent shifting with optimized AeroGlide lower pulley, ceramic bearings.