
SHIMANO 4 PORT JUNCTION EW JC304 EW-SD300 PORT X 4
Di2 Frame Junction BoxFeatures-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..com/