API Filstar XP Filter Micro-Filtration Pads, 3-Count Contains one (1) API FILSTAR XP MICROFILTRATION Aquarium Canister Filter Filtration Pads 3-Count Ideal to filter finest particles in combination with thicker foam pads. Designed to fit API FILSTAR xP canisters filters. For use in freshwater and saltwater aquariums. Replace every time water is changed or at least once a month.