Filter Housings | Water Filtration WPP Series Polypropylene Filter Bag DOWNLOAD BROCHURE The WPP Series (Polypropylene Felt) filter bags are manufactured from felt because of it’s high solids loading capabilities in comparison to similar mesh fabrics. The Filter Bags are manufactured in an ISO9001 certified factory and are a Nominal micron rating ranging from, 0.5 … Continue reading WPP Series Polypropylene Filter Bag