The SRAM X01 Eagle Rear Derailleur features an updated cage architecture to provide better chain management. Rear Derailleur Mount Type: 10x1 Standard Drivetrain Speeds: 12 Cage Length: Long Chain Wrap Capacity (teeth): 42 teeth Largest Cog: 52 Rear Der/Shifter Compatibility: SRAM X-Actuation Type 3 clutch is smoother and more durable 14T lower pulley Includes a chain gap tool that makes it easy to set up the correct chain length Designed for a max 52t large cog