TRP TR12 Rear Derailleur and Shifter Kit - BlackTRP TR12 Rear Derailleur and Shifter Kit Black. The 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