The most advanced level of shifting technology: at the touch of a switch Dura-Ace Di2 is quick shifting, smooth, and effortless The removal of traditional mechanical cables in favour of electrical wires eliminates poor shifting caused by contaminates, corrosion and stretching, and also provides effortless gear shifts Simply pressing tactile buttons allows effortless and comfortable shifting even when your hands are cold Shift switches to be used in conjunction with ST-7971 TT aero levers which can be located on the aero extensions as a replacement for traditional mechanical bar end shifters These switches now give the added option of being able to operate the gears from either the aero extension or the aero ST-7971 brake lever previously not possible on a TT set up These Di2 switches are also compatible with the FlightDeck computer (SC-7900), measuring important data such as heart rate, altitude, cadence, gear position, battery indicator, and more Switches are supplied without electrical cables, as these need to be ordered separately to suit