General: EZ flow II disposable filters are designed for protection of furnace and Central air units in residential and light commercial applications. Construction of both models is identical except for the media retainer. The EZ flow II has no media retainer. The media itself is adhered directly to the frame for non-metallic applications.^^Construction: 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 media support of 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 listed.