The Pet Life ® 'Moda-Pure' Filtered Dog and Cat Fountain Replacement Filters are sold as a 3 Pack and specifically designed for use with the Moda-Pure Filtered Fountain. Each Filter is meant to last for approximately 90 days of usage for a total of up to 270 days. Designed to remove impurities in water and assist in the removal of Chemicals, Heavy Metals and Bacteria found in un-filtered water.