This MasterCool exterior grille cover is engineered with durable polyester, which protects your evaporative cooler from anything Mother Nature can manage to send its way. The washable fabric is easy to maintain and prevents pollen & other debris from entering into your home. For best results, pair it with the MasterCool interior grille cover. MasterCool is a registered trademark of Champion Cooler Corporation. WARNING: This product can expose you to chemicals including benzene which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.