It's a roll-up, magnetic, super-fake sunroof for your car. While it's completely useless, unless you have a dent you're trying to cover up there, it makes it look like you splurged for the extra bucks on your ride. Holy sweet fakeness.

Just in case you have an important meeting with somebody you want to impress and they are going to see the roof of your car, somehow. This is a good thing to have for that occasion. They may notice the sunroof and think you spent the extra bill$ on a sunroof, when actually it's fake. I find myself in these situations all the time.