SRAM Apex Rear Derailleur - 11 Speed, Long Cage, BlackApex derailleurs share all the compatibilty and many of the featrues of higher priced options. The 1x specific X Horizon derailleur design has arrived at the affordable Apex level 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 Pulleys have sealed cartridge bearings Aluminum cage and parallelogram Item