The sponge filter fits the edge of the aquarium to save space.The sponge medium is harmless to fish and it's suitable for both fresh and saltwater environments. The sponge filter can trap debris and avoid clogging. Easy to operate,use one end of an air hose connected to the filter, and the other end connected to an air pump. A check valve can be installed on the air hose to prevent backflow of water. Recommend tank size: up to 125 gallon, Dimension: 4.5" D X 5.5"H Includes: 2 Pcs Sponge Filters, 1 Piece of 8 Feet Clear Standard 3/16" Airline Tubing, 2 Pcs Check Valves, 4 Pcs Suction Cups ,2 Pcs Y-shaped Connectors 2 Pcs Large Sponge Filter Kit With Airline Tubing, Air Pump Valves, Suction Cups For 125 Gallon Tank