High quality drinking water: The filter is made of fine activated carbon polymer filter fibre, which can eliminate bad taste and odours, keeping the water fresh from pet fountains, let your pet be able to replenish the cleanest fresh water every day. Multi-layer filtration: The effective layered filtration system can remove chlorine, sediment and volatile organic compounds, and can effectively prevent the pump from clogging and extend the life of the cat / dog fountain. Perfect compatibility: Compatible with: PEDY, ISYOUNG, YOUTHINK and Hommii Flower Fountains. Note: Not suitable for Catit Fountain Cycle used: the filter lasts longer and requires less frequent changes than normal activated carbon filters. We recommend replacing the filter every four weeks to keep the water clean.