The screen protects the appliance from intrusion of rodents. The stainless steel screen is corrosive resistant and includes a 1/4” mesh opening for maximum air flow. The interference fit makes it easy to install and easy to remove during freezing temperatures when the condensation might freeze the opening shut. Please refer to NIBCO technical data sheets and catalogs for engineering and installation information. Polyvinyl chloride (PVC) is the most frequently specified of all thermoplastic materials because of its light weight, durability, and cost-effectiveness. NIBCO® plastic fittings are backed by a 5-year limited warranty. Because of its longstanding reputation for innovation and precision in design and manufacturing, NIBCO is the preferred brand in the industry.