Marineland's Filter Foam provides a large surface area for screening out and trapping particulate debris. Fits C-Series and Magniflow 160 & 220 Canister Filters. To start up: Rinse Filter Foam in clean room temperature water and drain. Place 2 filter foam pads in the bottom filter tray. Rinse monthly with established aquarium water. Replace every 6 months. Screens out Dirt and Debris.Rite-Size S. Enhances Biological Filtration.