Valterra' s A10-1301VP Bug Screen for Outside RV Furnace Vents are designed to fit most Duo-Thermo and Suburban furnace vents. They are easy to install and offer minimal airflow restriction while ensuring that your vents stay free from costly invasion by unwanted pests (nesting insects, birds, and rodents). An installation tool and two spring fasteners are included with each bug screen. Screens should be inspected monthly and cleaned when necessary to maintain proper airflow. Screen measures 2. 8" x 1. 2".