For internal DI2 wire routing, SHIMANO's SM-JC41 Junction B is the central connector for DI2 systems. Wires from the front and rear derailleurs, cockpit area, and battery all plug into the 4-port SM-JC41 junction, which is housed inside the bike frame.

All of the component and battery wires meet here before running out to their respective components - all of the wires that connect to the junction box use the same connector to make assembly that much easier.

This junction box is only made to be mounted internally on frames specially designed for an internally routed system.

Features

• ULTEGRA R8050 Series: Compatible with Shimano e-tube Di2 systems (not compatible with Dura Ace 7970)
• For internal wiring setups only
• 4 x SD50 ports
• Made in Japan
• Shimano part number ISMJC41

For more information, visit the Shimano Product webpage