【 Suitable 84oz/2.5L Sq. Cat Water Fountain】:The pet drinking water fountain filters are intended compatible with 84oz/2.5L square cat drinking water fountain. https://kattengekte.com/shop/cat-water-fountain/cat-water-fountain-filter/cat-water-fountain-replacement-filters-cotton-activated-carbon-replacement-water-fountain-filter-for-84oz-2-5l-automatic-pet-water-fountain-dispenser-with-4-pack-replacement-filters2-pack-sponges/