The ULTEGRA RD-R8150 12 speed Di2 electronic rear derailleur integrates the system charging port and a wireless connectivity unit all while delivering super fast, precise shifting worth of any podium. A single cage length shifts cassettes from 11-30 to 11-34 bringing new versatility.* Compact SHADOW design includes an integrated wireless unit, charger, switch and LED status indicator.* Wider range capacity: compatible with 11-30 and 11-34T 12-speed cassettes* Super fast shifting* Integrated D-FLY Connectivity* Maximum low sprocket: 34T