The SM-EW90-A 3-Port Cockpit Junction Box allows for the connection of one pair of Di2 shifters to the frame junction box using three SD50 E-tube wires. It is designed for Dura-Ace Di2 9070 and features an LED battery charge level indicator, rear derailleur adjustment mode, and an internal battery charging port.
Similarly, the SM-EW90-B 5-Port Cockpit Junction Box enables the connection of up to two pairs of Di2 shifters to the frame junction box using five SD50 E-tube wires. It also supports Dura-Ace Di2 9070 and provides the same LED battery charge level indicator, rear derailleur adjustment mode, and internal battery charging port functionalities.
It's important to note that all Di2 components on the bicycle should have the same firmware version. Mixing Di2 components with different firmware versions can lead to malfunctions.