Nature2 Pool Purifier Cartridge for inground pools. Cartridge Model N2CG45 for 35,000 to 45,000 gallon pools. Fits all Nature2 inground purifiers Visions, Claritec, Clear Vision, Eco Spring, Aquatech, Visi Pure, White River, Fafco, California, Hawaiian. Unit lasts for 1 season or 6 months.