Marineland Rite-Size A Cartridge Refills, 12-Pack (2 Packs with 6 Filters per Pack), Aquarium Penguin Power Filter Cartridges 12-Pack (2 Packages with 6 Filters Per Package) Marineland Rite-Size Cartridge A Each cartridge is pre-assembled Meets the highest standards of water purification and operational ease Rite-Size A fits Penguin 100B, Mini, and 99B.Rite-Size B fits Penguin 150B, 110B, and 125B.Rite Size C fits Penguin 200B, 350B, 170B, and 330B.