Catit Drinking Fountain Replacement Carbon Filter Cartridge for Fresh & Clear Drinking Fountain - 3-Pack (12-Pack) Catit Drinking Fountain Replacement Carbon Filter Cartridge for Fresh & Clear Drinking Fountain - 12 Packs of 3 Replacement cartridge for the Catit Design Fresh & Clear Drinking Fountain Works to collect debris, food and sediment Helps reduce odors and impurities in your cat's drinking water 12 Packs (Each Pack Contains 3 Cartridges / 36 Cartridges Total)