Featuring 35 square feet of 3-ounce basis weight media made of 100-percent polyester Reemay material this Unicel 4CH-935 Cartridge Filter for Hot Tubs 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 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 cap is made of durable plastic that resists damage from chemicals and includes a 2-inch female SAE thread and a v-groove semi-circular handle for easy removal and replacement. This 4CH-935 model of spa filters is compatible with various hot tubs including Waterway Plastics Nordic Hot Tubs Rising Dragon and Master Spas. The Unicel 4CH-935 Spa Cartridge Filter is clearly the optimal choice to keep your hot tub or spa water sparkling.