The Aerostar® HEPA (Aluminum Separator) filter is constructed with an 18-gauge galvanized steel frame with a continuous band of media pleated back and forth over corrugated aluminum separators. These filters contain a two-part polyurethane, which assures a positive seal of the media pack and frame. The interlocking frame design with sealant placed behind the top and bottom flange allows unobstructed air flow and ease of filter handling. Available in different frame materials and a wide variety of gaskets to fit any application or filter housing. Gel Seal, no problem!