The XTR RD-M9120 is a 12 speed rear derailleur compatible with double chainring drivetrains. The XTR M9100 series of derailleurs brings a new level of drivetrain silence thank to decreased tension in the low gear position and an added bumper on the pulley cage. Larger 13T pulleys increase efficiency and chain management while compatibility with SHIMANO’s new 12-speed cassettes boosts range. Decreased rear derailleur tension at low gear position to prevent high chain tension Add bumper at rear derailleur pulley cage Bigger 13T pulley 10-45T 2×12-speed Enhance shifting performance Silent drivetrain Low profile design Low sprocket compatibility