Shimano di2 junction a sm ew90 a 3 port 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 this junction a is required to connect the shifters via e tube wires to the down tube junction wire battery level indicator feature e tube ew sd50 wires not included additional charging point when using internal battery gear index setup switch to allow fine