What is the official name of those covers that open and close over the headlights of some cars from the 1970s? I've seen Lincolns and Mercurys and even an Oldsmobile Toronado all from the 1970s that had light covers that covered the headlights when they were turned off and automatically opened and exposed the headlights when they were turned on.

However, I have seen cars that had these light covers in the open position when the headlights were off.

Did these covers serve a purpose or were they just a gimmick like the wipers on some Mercedes Benz headlights?