Shimano's Dura-Ace Di2 takes shifting to the next level. The Rear Wiring Kit connects to both the left and right shifters and Junction Box A (which displays battery power and allows manual adjusting). It also includes a battery mount, cable covers to route and hide the cables and a wire plug/unplug tool.
The Rear Wiring Kit is the wiring that runs from the stem/bar junction to the battery and derailleurs.
Battery sold separately.
Weight: 82 grams