The Marineland Mini Penguin Filter Cartridges are preassembled and filter water through a double thick polyfiber pad that traps more waste and dirt particles than conventional filter cartridges. Each disposable 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 unwanted odors. It's better than a separate bag. The patented ribbed back design evenly distributes carbon for maximum water-to-carbon contact. No "tea bag" effect...just crystal clear, crystal clean water. Performs mechanical and chemical filtration.