The Aqua-Tech EZ-Change Aquarium Filter #2 Cartridge is a set of three filter cartridges designed for aquariums with a tank capacity of 10-20 gallons. These cartridges are compatible with all types of water and are specifically made by the Aqua-Tech brand to ensure quality and efficiency in filtering aquarium water. Easy to install and replace, these cartridges provide a convenient solution for maintaining clean and healthy water in your aquatic environment.