Window vent, what do I have?

[goransons]

It clips into a early 60's front window (or back), has lift up, slide out doors that have almost a commercial kitchen vent grease screen in it. Clearly to vent the trailer either in storms or down the road. Was installed at the same time as the rock guard, looks stock. Rock guard was never attached to the trailer skin, just to the sides of this insert. I'd love to find out the name of this. I've searched the archives but no luck.