Set of 2 Catit Fresh & Clear Fountain Filters for us with the Catit Fresh & Clear Stainless Steel Drinking Fountain. The premium quality filter collects large particles and debris, helps reduce odours and absorbs impurities. The Dual Action filters are of Catit quality and are guaranteed to safely and optimally purify your cat's drinking water for approximately 30 days. After 30 days, filtration effects with start to gradually decrease and bacteria may start to form within the fountain reservoir. Replace your filter every month, or sooner if the filter is saturated. Rinse the filter under running water and place into designated area in the fountain.