Drinkwell Foam Replacement Pre-Filters - 8 Filters Total (4 Packs with 2 Filters per Pack) 8 Filters Total (4 Packs with 2 Filters per Pack) Drinkwell Foam Replacement Pre-Filters Compatible with Drinkwell Stainless Multi-Pet, Avalon, Pagoda and Sedona Pet Fountains Replaceable foam filter catches hair and debris keeping water clean Protects the pump and extends the life of your fountain Change every 1-2 months to maintain your pet fountain