• Economically and environmentally friendly frame has a one-piece design • No media retainer • Fiberglass or synthetic media • Available in 1″ and 2″ models • Available in all standard sizes and custom sizes • Designed for protection of furnace and central air units in residential and light commercial applications • UL Classified Merv 4 Media Type: Specially formulated microfiberglass - Synthetic Max Operating Temperature: 180˚F (82˚C).