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 Hayward pool and spa filter models C-225, CX225-RE also fits Apollo, Emerald, Sonoma spa filters.Measures 4-5/8-inch diameter by 11-7/8-inch length. 2-1/8-Inch top hole, 2-1/8-inch bottom hole. 2-1/8-Inch open top style and 2-1/8-inch open bottom style. 25-Square feet area, weighs 3-ounce. Replaces Unicel, Pleacto and Aladdin filter cartridge models C-4325, PA225-4/M4, 12501.