The 2.75 inch diameter by 7 inch length felt filter sock with plastic ring is designed specifically for Fiji Cube AIO tanks, providing essential filtration to maintain clear and healthy water conditions in your aquarium. Made from high-quality felt material, these socks effectively capture fine particulates down to a micron rating of 200 microns, ensuring that free-floating debris is efficiently removed from the tank water. Each filter sock comes equipped with a plastic ring for secure placement within the tank, making them easy to install and replace as needed.