The foam filters catch pet hair and other debris floating in the water, providing cleaner water for your best friend. The foam filter helps keep the fountain pump cleaner and maintain the fountain’s flow rate. The 2-pack of filters is compatible with the PetSafe® Drinkwell® 1/2 Gallon, 1 Gallon, 2 Gallon, Butterfly, Avalon, Pagoda, Seascape, Stainless Multi-Pet, Sedona, Seaside and Creekside Pet Fountains.