Experience electric transmission with the Shimano Ultegra Di2 Group. SM-JC40 external connection box. Reference: ISMJC40 External Connection Box SM-JC40 Shimano Ultegra Di2 Features: External Connection Box SM-JC40 Shimano Ultegra Di2. Indispensable in the case of external mounting of your electrical wiring, this junction box allows you to connect the electric wire of the front derailleur, the electric wire of the rear derailleur, the electrical junction wire and the electric wire for battery attachment. Depending on the size of your frame, adjust the wiring mount. Colour: black. Compatible with Shimano Ultegra Di2 transmission. See instructions above for wiring adjustment. Find all the Shimano technical manual to properly mount your Ultegra Di2 techdocs group. Shimano Com/media/techdocs/content/cycle/SI/Ultegra/UltegraDi2/DM-0001A-002-FRE_v1_m56577569830778812. PDF