TRP TR12 Rear Derailleur and Shifter Kit - BlackThe TRP TR12 drivetrain system brings World Cup downhill shifting technologies to the trails. The 12 speed design is the result of a collaboration between TRP, rider Aaron Gwin, and his mechanic John Hall. This advanced derailleur includes a Hall Lock a lever integrated into the B knuckle mount that locks out the main pivot bolt to prevent your derailleur from lifting, slapping and making noise The Hall Lock can be turned on or off, and the clamping