The Shimano BT-DN110-A Built-In Type Di2 Battery is ...
the power source for Shimano's 11 speed Di2 derailleurs and shifters. Its thin, sleek profile allows the battery to fit in seatposts or frames for a clean look.
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 ...