Cartridges are produced with genuine Reemay filter media and durable polyurethane end caps. Prevents harmful bacteria from growing on the cartridge. Less bacteria results in a reduction of foul odors, algae, black mold and other harmful contaminants which foul a cartridge. Antimicrobial protection lasts as long as the cartridge itself. Easier to clean than any other filter. 100 percent polyester core for strength and durability. Polyester Microban sheath for ease of maintenance. Extruded and reinforced PVC center cores. Embossed part numbers. Break-resistant bands. No pad adapters needed. Fits Saratoga spas and Dimension one spas filter models PSG40N, 1561-13.Measures 4-5/8-inch diameter by 15-inch length. Closed top hole, 1-1/4-inch bottom hole. Top crescent handle style, 1-1/4-inch SAE bottom style. 40-Square feet area and weighs 3-ounce. Replaces Unicel, Pleatco filter cartridge models 4CH-940, PDO-UF40P2.