SRAM Rival 1 Rear Derailleur - 11 Speed Medium Cage Black/SilverSRAM Rival 1 Rear Derailleur 11 Speed Medium Cage Black Silver. The 1x specific X Horizon derailleur design provides excellent chain control and shifts well regardless of cassette size. Roller bearing clutch and parallelogram design combine to minimize chain bounce making the drive train safer and quieter over rough terrain Not compatible with multiple chainring drive trains TECH SPECS Cage Length Medium Chain Wrap Capacity (teeth) 32 Color Black