a filter assembly for use in the filtration of medical treatment liquids is disclosed . the filter assembly includes a strip of porous filter media , first enclosure means , and a second enclosure means . an inlet connector is connected to inlet end of the filter assembly and an outlet connector member is connected to an outlet end of the filter assembly . the first and second enclosure means , are formed of strips of flexible plastic material having longitudinal edges , which are ultrasonically welded to the filter media . dimples , are formed in the first and second enclosure means , , respectively , and are ultrasonically welded to the filter media .