in a filter element , such as an air filter element used for filtering engine air or cabin air in vehicles , a pleated filter media is disposed within a plastic frame and retained therein by the same material which is used to form a gasket for sealing with a housing in which the filter element is mounted . the gasket is formed of polyurethane foam or any other flexible sealing material such as plastisol or silicone and is cast molded around the outer periphery of the frame over a plurality of interlocking tabs . the seal is therefore mechanically locked to the frame as well as being adhered to the frame .