Di2 4-Port Junction Box EW JC304 Black For E Tube Systems Ultra Compact And Lightweight Junction Hub Built Tough For Rugged Ride Lets You Connect Up To Four Electro Components For Smooth Reliable Shifting On Any Ride

EW JC304 4-Port Di2 Junction Box for ETube systems
✔️ Single unit, four-port Di2 hub for ETube components

The EW-JC304 is a four-port junction box that serves as the central hub for Shimano Di2 E‑Tube systems. This compact, lightweight unit links shifters, front and rear derailleurs, cockpit controls, and battery mount for streamlined electronic shifting on road, mountain, and gravel bikes.

✅ Compact, lightweight design for rugged rides
✅ Connects up to four electronic components (front/rear derailleurs, cockpit controls, battery mount)
✅ Compatible with EW-SD300 cables and firmware updates via the e‑Tube System Checker
✅ Black color for clean frame integration

💡 What is a Di2 4-Port Junction Box used for in ETube systems and why choose EW-JC304?

The EW-JC304 is a central hub that routes power and signals between shifters, derailleurs, cockpit controls, and the battery, enabling synchronized electronic shifting across road, mountain, and gravel bikes.

- Handy for clean wiring and precise gear changes
- Supports up to four Di2 connections with EW-SD300 cables
- Keeps components up to date with firmware via the e-Tube checker
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