With its unique honeycomb structure design, this filter bag is able to efficiently capture fine impurities and significantly improve water clarity The filter bag is made of high quality non-woven material with good water permeability and durability Package includes 6 Pack 4 Inch honeycomb design filter sock for fish tank, the size is 4 inch ring by 11.8 inch long It is recommended to change the fish tank filter regularly to ensure the filtration effect as well as the cleanliness of the fish tank, it's better to change every 3 months If you have any questions about the product, feel free to contact the Beaufan team at any time, and we will address your needs as soon as possible Beaufan 6 Pack 4 Inch 150 Micron Honeycomb Filter Socks Compatible with Waterbox MARINE X 60.2, 90.3, and 110.4, Aquarium Filter Sock 3D Honeycomb Design Filter Sock, 4 Inch Ring by 11.8 Inch Long