So anyone know what this is?

So anyone know what is up with this? Figured anything to do with air shocks or air ride would require a air tank somewhere on the car.

No air tank, if you remove the cap you can pump up the air shocks through that fitting.

Look at the second pic, it looks like an air line running around the rear of the gas tank.

Problem is, when running air shocks (which I personally don't like), they should be plumbed independently so when cornering the air doesn't push from one shock to the other with the weight transfer.