It's a $20 cable that you get from BMW, that plugs into your head unit in the back, there is actually a port for it. Then you get another $15 cable to connect from it, to your iphone. The AUX input appears on your head unit, and you listen to your Iphone. Steering and radio controls don't control your iphone, but I honestly don't care about that. It sounds great, and doesn't cost much. Plus I get to connect whatever device I want.