Shimano Dura Ace Di2 9070 11Spd Rear Gear.- Digital Integrated Intelligence or Di2: with programmed automatic motion at the touch of a switch the Dura-Ace Di2 rear derailleur is quick, smooth and effortless, making for unmatched drivetrain efficiency. - Programmed automatic motion at the touch of a switch makes this derailleur quick, smooth and effortless to shift. - The removal of traditional mechanical cables in favour of electrical wires not only eliminates poor shifting caused by contaminates, corrosion and stretching. - Derailleur contains a saver (fuse) function, where the inner structure is protected from strong impacts. - 11-28T wide gear ratio capacity will cater for compact setups as well as the traditional road double. - Full carbon fibre inner and outer pulley plates enhance rigidity and reduce weight. - Titanium B axle bolt for further weight savings. - High tolerance cold forged aluminium link plates and body construction is extremely light and durable. - Four self-lubricating micro-machined fluorine-coated link pivot bushings provide low-friction shifting. - Pulleys are made of tough DuPont Zytel for longer life and less chain noise. - 11-speed E-tube Di2 compatible. - Max front difference: 16T. - Total capacity: 33T. - Weight is 217 grams.