The Aqua Spa 20 Sq. Ft. Compatible Pool/Spa Filter is a compatible replacement water filter cartridge for swimming pool and spa water filtration. This Filbur pool filter uses pleated polyester media to trap particles and contaminants. This pleated pool filter cartridge offers strength and durability through reinforced PVC center cores that prevent cracks and collapse.This Filbur spa filter includes wide support bands that promote optimal water flow and resist breaks. In addition, this compatible Aqua Spa filter includesend caps that fight the growth of mold and bacteria, which can cause unpleasant odors or contaminate your pool/spa water. Features: Area: 20 sq. ft. Closed top hole Top style: Handle Bottom style: 1 7/8" Open