Wasps, mud daubers, birds, and rodents pose a serious threat to the furnace on your RV. They can enter through the furnace vents and cause serious damage by building nests that interfere with air flow. The Camco Model FUR 500 Flying Insect RV Furnace Screen fits Atwood Hydroflame furnaces that do not have an access door. This easy-to-install screen will help ensure that your furnace vent stays free from costly invasion by unwanted pests.• Screen measures 3-5/8" dia. x 1-5/16" tall• Fits vent of Atwood Hydroflame Furnaces that do not have access doors• Protects the furnace from flying insect nests• Easy to install with included tool• Heavy-duty stainless steel mesh cover Heavy-duty stainless steel mesh cover Easy to install with included tool Screen measures 3-5/8"" dia. x 1-5/16"" tall | Camco Flying Insect Screen for Atwood 2004 Furnace Vent