Camco 42144 Flying Insect Screen - FUR 500 Screen measures 3-5/8" diameter x 1-5/16" tall Fits vent of Atwood Hydroflame Furnaces that do not have access doors, and exhaust vent of Girard Tankless Water Heater Protects the furnace from flying insect nests Easy to install, includes tool Heavy-duty stainless steel mesh cover