Shimano SM-JC40 Di2 External Frame Junction Box 4-Port

Shimano Di2 Frame Junction Box

• Mounts underneath the bottom bracket shell
• 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/