This Junction box is used to connect the shifters via E-tube wires to the downtube junction wire. To accomplish this, a 3-port design is used with one for the downtube wire to bottom bracket junction and four for shifter connection.
The Shimano Di2 SM-EW90-A Junction Box 3-Port with Strap Mount is suitable for competitive cyclists who need an easy-to-install, flexible junction box for their Di2 systems, offering compact and durable design.
