The shimano dura ace rd 9070 di2 11 speed rear derailleur features digital integrated intellegence di2 thanks to its programmed automatic motion at the touch of a switch this rear derailleur is quick smooth and effortless to shift providing you with unmatched drivetrain efficiency the removal of traditional mechanical cables in favour of electrical wires eliminates poor shifting caused by contamination corrosion and stretching the derailleur contains a saver fuse function w