Make sure that you keep the water in your spa or hot tub clean and inviting with the Intex PureSpa Filter Cartridge S1 It fits all compatible hot tub models making it versatile and easier to install. Suitable for home or commercial use this Intex filter cartridge needs to be replaced every two weeks to ensure proper sanitation. It s built from high-quality materials to capture debris and more for a refreshing and relaxing experience. This replacement filter cartridge comes in a pack of two making it easy to service multiple units or provide a spare to keep handy for later