Shake off the summer heat in a cool pool. Make a splash in the cleanest swimming pool in the neighborhood with Unicel C-8610 Replacement Filter Cartridge. Featuring 100 square feet of 4-ounce basis weight media made of 100-percent polyester Reemay material, this pool and spa cartridge filter ensures high performance and dependable filtration over time. The uniform pleats and Reemay media deliver higher dirt-holding capacity and more time between cleanings. Plus, the smooth surface of the media makes it easy to maintain, resists degradation from chemicals, stands strong under pressure, and holds up to the rigors of multiple cleanings. For optimal lifespan, clean the elements as per instructions and use a soft brush cleaning tool or filter cleaner for easy maintenance. Please note that the cartridge life depends on routine maintenance and pool or spa water chemistry. Change your filter when there is a shorter cycle between cleaning, low water flow rate or high differential pressure, when the media has a tear, or if the center core collapses. The end caps are made of durable plastic that resists damage from chemicals and include a 4-inch ID, open (with molded gasket) configuration for easy removal and replacement. This C-8610 model of pool filters is compatible with Hayward Pool Products and Cal Spas. The Unicel C-8610 Cartridge Pool Filter is clearly the optimal choice to keep your hot tub or swimming pool water sparkling.