The Dura-Ace RD-R9250 rear derailleur integrates the system charging port and a wireless connectivity unit all while delivering super fast, precise shifting worthy of any podium. A single cage length shifts cassettes from 11-28 to 11-34, offering exceptional versatility.Features-Ultra-fast rear Di2 shifting-Compact design includes an integrated wireless unit, charger, switch-Wider range capacity-Max. low sprocket: 34t-CFRP rear derailleur plate-LED status indicator-Battery indicator, pairing, adjust mode etc.Item Specifications-Largest Cog:34-Rear Der/Shifter Compatibility: Road Di2-Rear Derailleur Mount Type: Rear Direct Mount-Rear Derailleur Mount Type:10x1 Standard-Drivetrain Speeds:12-Chain Wrap Capacity (teeth):37-Cage Length:Medium-Color:Black