Economy Fiberglass EZ Flow II disposable filters are designed for protection of furnace and central air units in residential and light commercial applications. The frame is made from heavy chipboard in a one-piece design that eliminates corner separation. The filtering media is continuous filament spun glass. A resinous bonding agent provides rigidity and resistance to media compression. The EZ Flow II is made to function without a retainer, by adhering the frame directly to the media which has a light skin to make it self retaining. Sealing is accomplished with a resilient hot-melt adhesive running the full perimeter of the frame on both upstream and downstream sides. UL marking appears on the filter frame. These filters have been tested by Underwriters Laboratories Inc. and are classified as UL 900 Class 2 for flammability. MERV 4.