Quick smooth and effortless to shift the shimano dura ace di2 rd 9070 bicycle rear derailleur 11 speed provides programmed automatic motion at the touch of a button with automatic crash pad protection which moves the cage out of harms way if you take a fall it also features electrical wires to produce effortless gear shifts lightweight and durable the derailleur have four self lubricating micro machined fluorine coated link pivot bushings to reduce friction whilst the dupont zytel pull