The Rochester Synthetic Pocket filter is constructed with a moisture resistant, ultrasonically welded media. The synthetic media consists of strategically layered and blended melt-blown polypropylene fibers fastened to a non-shed, high density polypropylene backing. This design creates a dual-stage filtration effect with the final layer capturing the smaller particulate from the air stream. The patented ultrasonic welding process allows Rochester to manufacture a product without creating stich holes in the media and still be able to provide an increase in surface area. Vertical separators are incorporated into each pocket to effectively channel air throughout the media to prevent excessive turbulence and allow even contaminant loading throughout the life of the filter. The header is constructed of 26 gauge galvanized steel with rolled edges to provide rigid support to the filter face and allow for easier handling. The Synthetic Pocket filter offers high efficiency filtration while maintaining low resistance to air flow.