High Rate Sand Filtration in 3 model sizes ranging from 2.2 to 4.9 sq. ft. of filter area. Molded two-piece fiberglass tanks are noncorrosive and have a low profile design. All models have 2" PVC unions on inlet and outlet ports. A 1.5" port in the top of the tank allows installation of sand media without unbolting tanks at the center flange. Available with a choice between 2-position molded ABS or bronze backwash valves, or a 6-position multiport valve. Filters may be easily combined with a circulation pump and valve using the accessory base extension and piping kits, ordered separately. NSF Standard 50 approved for residential and public swimming pools when sized at a maximum of 20 GPM/Sq. Ft. of filter area for the listed models.