The PetSafe Pet Fountain Replacement Foam Filters catch pet hair and debris in the water before they reach the pump, providing cleaner water for your pet. These foam filters help keep the pump cleaner and help maintain the fountain's flow rate. The foam filter helps protect and extend the life of your fountain pump and keeps it clean. Easy to remove when you clean your pump and replace the foam filter; change every 1-2 months to maintain your pet fountain. These filters are sold in a 2-pack and are compatible with the PetSafe 1.8 Litre, 3.7 Litre, 7.5 Litre, Oasys, Butterfly, Pagoda, Stainless 360, Sedona, Seaside?and Streamside Pet Fountains. Trust PetSafe to help keep your pet healthy, safe and happy.