The new revolutionary Shade4Utm system keeps the sun from coming through the windshield and the rear window before it gets a chance to start heating up the air INSIDE your car, so the car stays cooler longer.
Typical sun shade
These work up to a certain point, then the heated air begins to cycle in the car until all the air is as if you hadn’t put it in at all. But why let the sun into the car at all? That’s what never made sense to me.