Key Features: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,The removal of traditional mechanical cables in favour of electrical wires eliminates poor shifting caused by contaminates, corrosion and stretching, and also gives effortless gear shifts,Simply pressing tactile buttons allows effortless and comfortable shifting even when your hands are cold,Climbing twin button satellite shift switch is used to operate the rear derailleur whilst your hands are on the top of the bars, one button up , one button down,To be plugged direct in to E-tube drop bar STI shifters,Shift switch is supplied with 260.5 mm E-tube electrical cables installed,Weight is 30 grams a pair.