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This is the Shimano Ultegra Di2 Internal Junction Box. This box is referred to as the junction box "B" on a Di2 build. The SM-JC41 is for use with internal wiring setups and is the main center of e-tube Di2 systems. For external wiring setups see the SM-JC40.
Note: For internal use only!
This product was added to our catalog on July 26, 2014