The preassembled Emperor Filter Cartridges filter aquarium water through a 44-square inch filter pad. Made of double thick polyfiber, it traps more waste and dirt particles. Inside, each disposable filter cartridge contains two full ounces of Black Diamond Activated Carbon. It works longer and faster to absorb harmful pollutants which discolor aquarium water and cause odors. It's better than a filter bag: just shake and rinse. The patented ribbed back design evenly distributes carbon for maximum aquarium water-to-carbon contact. No tea bag effect...just crystal clear, clean aquarium water. Emperor Filter Cartridges provide supreme mechanical and biological aquarium filtration in both freshwater and saltwater aquariums. Designed for both the Emperor 280 Filter and Emperor 400 Filter models.