AQUEON - Replacement Filter Cartridge Large - 12 CartridgesDESCRIPTION Patented Aqueon dual sided dense floss cartridges contain over 25% more activated carbon than the leading brands. These unique cartridges were designed to ensure even distribution of carbon throughout for more thorough filtration and longer cartridge life. High quality activated carbon keeps water clean Align cartridge bottom key slot for an accurate fit inside the filter Rinse under water to remove carbon dust before replacing For optimal