The Shimano Dura-Ace Di2 RD-R9250 Rear Derailleur brings a whole new level of ease to electronic shifting. Compared to previous Di2 derailleurs, shifts are 58% faster and more precise. Available in only a single cage length, it is now compatible with wider range cassettes, from 28 to 34 tooth cogs max. With an integrated charging port and LED status indicator light, keeping your shifting powered up and connected has never been simpler. Features: Fastest ever rear shifting, 58% faster than RD-R9150 Compact design includes an integrated wireless unit, charger, switch LED status indicator: Battery indicator, Pairing, Adjust mode etc. Wider range capacity: max. sprocket: 34T Carbon fiber reinforced polymer rear derailleur plate Specifications: Speed: 12 Speed Shifter Compatibility: Shimano Di2 Shift Mechanism: Electronic (Wireless/Wired) Max. Tooth: 34T Min. Tooth: 11T Chain Wrap Capacity: 39T Cage Material: Carbon Chain Retention: Shadow Color: Black Weight: 215g