Rio Nano Skimmer hang on filter. For aquariums up to 20 gallons. Simple installation and compact design. Includes intake venturi and needle wheel. Adjustable variable venturi with exclusive air/water mixing chamber. Filter cartridge with acivated carbon. Ozone compatible. Water level control. 110 gallons per hour pump.Dimensions: 7.25" x 10.25" x 11.5"