Provides both mechanical and biological filtration for aquarium. The air infusion chamber produces numerous minute bubbles which promotes gas exchange process and increases dissolved oxygen level in tank water.，It's easy to set up. Just connect the unit with an air pump thru an airline. It provides both aeration and filtration for your tank.，The sponge traps waste particles mechanically and cleans the water without trapping baby fish. It keeps water clean and clear.，Product dimensions: 6.5"L x 2.4"W x 9.5"H sponge dimensions: 2.4"D x 4.5"H. They are useful for as breeding filter or as secondary filter. Or they can be used as pre-filtration unit by fitting to an external or a top filter.，Max tank size: up to 55 gallon each filter. Package includes: 2 pcs of sponge filters in a poly bag.