The removal of traditional mechanical cables in favour of electrical wires not only eliminates poor shifting caused by contaminates, corrosion and stretching, but provides effortless gear shifts. The SM-EW90-B 5 Port Di2 Junction A from Shimano is required to connect the shifters via E-tube wires to the down tube junction wire. This one features a battery level indicator and an additional charging point when using an internal battery and a gear index setup switch to allow fine tuning via shifter buttons. Sold individually, Black only.