Manufactured of galvanized steel and powder coated as a primer. All welded construction eliminates rattle. Supplied with a unique waterproof baffle plate and drain ports in the corners to allow water to escape. Complete unit includes outside vent body with a 7-1/4" dia. zinc plated steel inside grille and gasket. Can be mounted on roof or front of trailers. Recommended for use on busses, emergency vehicles, horse trailers, truck bodies, tractor cabs and trailer vans.