Shimano EW-JC304 Di2 Junction Box - 4 Ports, Use With EW-SD300

Shimano Di2 Frame Junction Box

- Frame Junction Box connects via SD50 E-tube wires to four different points: front derailleur, rear derailleur, cockpit junction box and battery mount
- All Di2 components on the bicycle require the same firmware version. Using Di2 components with different firmware versions may cause malfunctions
- Use Di2 system checker to update component firmware from http://e-tubeproject.shimano.com/