SRAM SRAM X01 Eagle 12-Speed Type 3 Rear Derailleur, BlackX Horizon parallelogram minimizes chain slap and is maintains constant gap with the 10 50 Eagle cassette. 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 Rear Derailleur Mount Type: 10x1 Standard Drivetrain Speeds: 12 Cage Length: Long Chain Wrap Capacity (teeth): 40 teeth Largest Cog: 50 Color: Black Weight: 276 g Rear Der Shifter Compatibility: SRAM X