As an improvement over the Dura-Ace Di2 setup, the Ultegra Di2 group uses a junction box to simplify the wiring, giving you a cleaner look with easier setup. The junction box mounts under your bottom bracket shell (for external wiring) and connects the wires coming from the derailleurs, levers and battery.
Item No. » SH-SD50JB
Nashbar: $34.991 or more: $34.99