The Powerline Top Mount Sand Filters offer the lastest in pool technology with smooth, efficient flow and totally balanced backwashing. These sand filters feature unitized construction of corrosion-proof, polymeric material and self-cleaning, 360 degree slotted laterals. A versatile, six position control valve offers easy operation and maximum efficiency. For use with in-ground pools of all types and sizes, in-ground spas and water features, ponds or fountains. Available in 21″ and 24″ complete with unions.