Basically this thing goes under the front bumper and replaces the plastic undertray with an aluminum one. Lots of people have lost their plastic ones on the street (including me) and this is a stronger alternative, and I can't see it falling off anytime soon.
At least this way i don't have to worry about debris coming up and slamming onto a rad hose or something, plus it keeps a lot of air from coming into the engine bay from the bottom of the car.
I had to make a couple cuts along the front edge due to my non-OEM bumper cover, but it fits.
This is what the underpanel itself looks like
By the way, these are not my pictures, I don't have a digital camera (yet), but at least you get the idea.
And Kirasir, no I haven't forgotten, msg me about this when you can.