The Mainstays Type VI Inflatable Hot Tub Replacement Filter Cartridge is a set of two plastic cartridges designed for use in hot tubs, above ground pools, and in ground pools. With a capacity of 1,000 gallons, these cartridges are easy to install and clean, making them a convenient and modern addition to your pool or spa. The cartridges are also salt water compatible, ensuring that your water remains crystal clear and refreshing for hours of enjoyment. Made by the trusted brand Mainstays, these filter cartridges are a reliable and essential component for maintaining a clean and clear pool or hot tub.