The Glasfloss Purapak extended surface bag filter shall incorporate an ultra-fine fiberglass media. Individual pockets shall be formed by span stitching down the length of the pockets to maximize the utilization of media. The stitching shall be coated with a thin line of hot melt adhesive to secure the thread to the media and seal any perforations in the media caused by sewing. The pockets shall be individually adhered to an internal aluminum tube header. Each individual pocket shall be fastened to the next by means of pocket support ribs, which are mechanically attached to the internal header. The entire assembly shall be encased in a galvanized steel header frame to prevent racking and possible bypass of unfiltered air. Glasfloss Excel and Purapak filters shall be Classified under U.L. standard 900. Excel and Purapak filters shall be rated to withstand temperatures up to 160 degrees Fahrenheit.