【Versatile】: These inflatable pool filter bags can be used for swimming pools, bathtubs and spas. 【Filtration】: The filter cartridges are designed to keep your bathtub water clean and clear. They are easy to install and maintain, requiring only regular rinsing under a faucet. If they remain dirty or discolored after washing, they should be replaced to avoid damaging the filter pump. 【Application】: Only applicable to inflatable swimming pools produced after 2020. 【Package Contents】: This package comes with two replacement filter cartridges suitable for spa bathtubs.