The Shimano Ultegra RD-R8150 Di2 12-Speed Rear Derailleur uses an Ultegra Shadow design with Di2 technology, shifting is easy and precise - just a light touch, as soft as a mouse click, is sufficient for the front or rear derailleur to instantaneously select the correct gear.Shimano Ultegra RD-R8150 Di2 12-Speed Rear Derailleur FeaturesThe rear derailleur is now the brains of the system with wireless connectivity to the shifters. It acts as the point the system is charged, provides ANT+ connection to 3rd party devices and replaces the handlebar junctionButton on the derailleur for Di2 operations, and LED light denotes synchronized shift mode, setting mode and charge requirementsSleek appearance...
Best Price: £379.99 from Leisure Lakes Bikes