SWELL. 14000-B20-65201. FILTER CAP. The Filter Cap lets you enjoy fresh-tasting tap water wherever you bring your S well Simply fill from the tap secure the cap and sip for instant filtration. This leak-free cap features a protective cover and an ergonomic drink-through spout. Our premium carbon filter meets NSF standards to reduce chlorine and particulates while improving taste and odor. The S well Filter Cap fits our 9oz and 17oz Original bottles and comes with one filter.