The Shimano Deore XT RD-M8100/M8120 rear derailleur is designed to provide smooth and stable shifting for 12-speed MTB drivetrains. - Offers fast and shockless shifting - The low-profile design includes a bumper added to the derailleur pulley cage - Shimano Shadow RD+ technology reduces chain slap and creates a quieter drivetrain - Includes large, 13T pulley - Long cage is designed to be used with 1x12 drivetrain systems - Rear Derailleur Mount Type: Shimano Rear Direct Mount, 10x1 Standard - Drivetrain Speeds: 12 - Cage Length: Long - Chain Wrap Capacity (teeth): 41 teeth - Largest Cog: 51 - Weight: 284 g - Rear Der/Shifter Compatibility: Shimano Mountain