I have an extra Camco insect screen cover for an Atwood (and others) furnace. It is a 3.5 inch round Camco #FUR500. Rather than toss it out, I'll mail it free to anyone who could use it. Shoot me a message if interested. I went with a much larger rectangular one for my Camplite because I decided to cover the entire furnace outside trim and not just the exhaust outlet.