Gaskets should be black. Nothing mounts on the outside of the louver, the gasket sticks to the underside outer rim of the louver, then screen, then backing plate, then hood. Don't think it's really meant to seal as their just ornaments but more to keep things from rattling around. If the ones you have have the foam on the bottom of the louver already you don't need anything else. If you have your assembly manual it's page 287.