Cage Aluminium Jockey Wheels 12t X-Sync pulley wheels Compatibility 1x 11 Extra Features Sealed cartridge bearings & X-Horizon design Weight 256g The SRAM X1 Rear Derailleur features a new, refined internal clutch mechanism with an incredible capacity for drivetrain efficiency, giving you every advantage on the trail. A lightweight but durable build ensures a favorable nature to shifting & gives an incredibly crisp ride.