The 20 Ppi Replacement Filter Foam For The Bio Master 250, 350, Or 600 Includes An Ultra-Coarse Replacement Filter Foam Customize Your Choice Of Filter Foams To Meet The Needs Of Your Aquarium Timing To Replace The Filter Foam Varies Upon Aquarium Size And The Number Of Fish And Plants Package Dimensions: 10.04" L X 2.05" W X 12.09" H