Actually, three of the bottom four are Airflow skirts. The bottom left skirt, which appears to be black, is for an Airstream. If you'll look closely at that black skirt, which fits the right side of the car, you'll notice that at the bottom trailing edge there is a small flair which points too the rear. The Airflow skirts don't have this flair and appear to have almost symmetrical leading and trailing bottom corners. Airstream skirts, like the black one, came in two different heights, although I