These high quality genuine filter cartridges have been designed to maintain clean, fresh tasting drinking water for your pet when fitted to your Cat Mate or Dog Mate Pet Fountain. The cartridges have a dual action. Firstly the fine polymer filter fibers trap hair, dirt and food residue thereby improving the life of the pump. Secondly the highly activated filter carbon removes odours including chlorine and greatly improves the taste of the water, making it attractive to even the fussiest pets. Genuine cartridges carry the Dog Mate and Cat Mate logo and use only high quality food grade extruded activated carbon. The cartridges arrive individually wrapped and should be rinsed in cold tap water before use. They should be replaced monthly, or sooner if they become clogged. After this time the activated carbon will no longer be effective even if the filter looks clean. Never run your fountain without a filter fitted. All Cat Mate and Dog Mate feeders, fountains and product accessories are manufactured from food grade, BPA free plastics