This opens up your Di2 to new levels, giving you the option to do on the road tuning of the Di2 set up also allows you to see on screen cell phone options. Keep in mind this Blue Tooth / Ant+ unit only works either outside frame or inside carbon or bamboo frames. I made the mistake of installing it inside of an aluminum bar.When it didn't work I thought I got a dud, I knew the wiring was and connection was good because everything else was working. I ordered another one and still nothing, with it out of the bar I hooked it up just out of curiosity and it worked. I then realized the issue and upon further research it was verified.