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 E-tube junction A controller has two in built wires for connection to the shifters  with one port for connection to the down tube wire
Will also require E-tube EW-SD50 wires from junction A to the rear mech  front mech  battery and the bottom bracket junction
Battery level indicator feature
Gear index setup switch to allow fine tuning via shifter buttons
Di2 cables cannot be cut to fit
Reliable and secure water resistant connectors
Cannot be used as charging point for internal battery
Brake cable mounting type