The Hagen A1366 is designed to fit the following aquarium filter:
The AquaClear 70 - A1366 Aquarium Nylon Bag - 2-Pack has fine mesh that holds small grained filter media. This AquaClear bag filter may be used in both fresh and saltwater aquariums. This aquarium nylon bag helps keep your aquarium clean and clear. These replacement nylon bags come in a convenient 2-pack.
The Hagen A1366 specifications: