Hello, I'm new to these forums and I apologize if my first question is so trivial. But we just bought a 2015 f350 super duty and as I'm learning about the truck, I have a question regarding a piece of plastic or rubber 'thing' (lack of a better term) on the drivers side roof. It almost looks like a fin. Any idea what that's used for?

 

Nevermind folks, I figured it out. It's the antena for SAT/XM radio.