The Hagen A900 is an aquarium filter with the following style filter:
The A900 Elite Biological Aquarium Sponge Filter is an air driven system that purifies aquarium water. This Hagen foam filter biologically transforms harmful wastes into harmless substances. This Elite sponge filter has a suction cup so the foam filter stays on aquarium sides. This water pump foam filter features gentle cleaning power that is safe for even the smallest fish, including baby fish or fry.
The Hagen A900 specifications: