The HCP0.45-20S4B is a high capacity polypropylene pleated cartridge Filter that is 98% efficient. The polypropylene media is rated with a 0.45 micron retention rating. This filter has a nominal length of 20 inches and has a S4 = 222 connection with flat end. The filter has a B = Buna gasket material. FDA listed materials: All materials comply with FDA Title 21 of the code of Federal Regulations Sections 174.5, and 177.1520, as applicable for food and beverage contact. See specification sheet for additional details. This product is made to order and is non-returnable.