I think he's talking about the moonroof in the newer benzes, they have a seperate headliner piece that you manually pull to cover the moonroof in case the sun gets too bright .
I'm interested in one for my 300E, If you find a cheap one, I'll take it.
1987 mercedes 300E
1995 e320 conversion(hated the 300e grill)
Monochromatic Paint (Custom Blue)
Flat Badged (front)
custom "carbon fiber" console
18 inch HP EVO rims
Sold! Now I drive a Monte Carlo SS