Zanyzap 12 Foam Pre-Filters for Drinkwell Stainless Steel 360, Lotus, Avalon, Pagoda Water Bowl (White) Improves filtration by trapping hair and other debris in the water Provides your pet with cleaner, healthier water Prolongs the life and flow rate of the filter pump Replace every 2-4 weeks, depending on usage Bulk packaged to save you money and protect our environment