Wasps, mud dauber nests, birds and rodents pose a serious threat to your RV furnace. These and other pests can enter through vents and openings and cause serious damage by building nests that interfere with airflow in and out of your furnace. Protect your valuable investment by installing Camco's Flying Insect Screen. This easy to install screen helps ensure that your furnace and fan stay safe from unwanted pests. The Camco 42155 Flying Insect Screen is designed for compatibility with Atwood AFMD model furnaces. It is made of heavy-duty stainless steel to last through many camping seasons.