The VGPS0.2-20S4-B Shelco MicroVantage VGPS Series vent grade hydrophobic polysulfone membrane filter cartridge. Absolute rated at 0.2 microns. This filter has a nominal length of 20 inches and has a S4 = 222 w/ Flat End endcap configuration. The filter has a B = Buna N gasket material to ensure a proper seals to the filter housing. This product is made to order and is non-returnable.