Polyester Felt Filter Bag | 100 Micron Rated | Aquariums, Coy Ponds, Pools, Reef Tank | Signed for Strength | Size #1, 7" x 16" | 3 Pack Filter bags have extra-thick felt for greater dirt-holding capacity than standard bags Polyester Seamless Felt Filter Bag,7" Diameter x 16-1/2" Height Using these filter socks will improve your aquarium's water clarity and quality. (3 Each/Pack) Aquarium Felt Filter Socks, 100 Micron, Custom Made In The USA