Replacement Pool Filter: C-8311 filter cartridge features 100 square feet (194 pleats) of 3-ounce basis weight media that catches debris and particles down to an average of 20 microns in size, keeping your water clear Optimal Debris Capture: Filter pool cartridge has sharp, uniform pleat folds that maximize water flow, minimize pressure loss, and allow full use of the pleat surface to hold more debris Filter Media: Constructed with 100-percent polyester Reemay material that balances dirt-holding capacity, cleanability, and durability with excellent chemical resistance properties End Cap Features: End cap design includes a 4-inch ID and an open configuration (with molded gasket) for easy cartridge removal and replacement; Durable plastic resists damage from chemicals Pool Fitment: Compatible with Hayward Pool Products; OD: 8-15/16 inches, Length: 17-3/8 inches