Catit Design Fresh & Clear Replacement Foam/Carbon Filter is designed for use with Catit Design's Fresh & Clear Drinking Fountain for Cats (Art. # 50053). This dual-function replaceable filter helps collect debris, food and sediment, helps reduce bad tastes and odors, as well as absorbs impurities present in tap water. Art #50057 and #55601 (blue and green) serve the same function. Package of 3. What's in the box? 1 x Catit Design Fresh & Clear Foam/Carbon Filters - 3 pack #hagen #catit #bowlandlitter #replacementfilter