The Marina Cool Air Pump is a reliable source for a wide variety of applications requiring the delivery of oxygen to aquariums, including delivering air to air-operated items such as air stones, air curtains, and air-actuated ornaments, as well as for generating water movement and turbulence. The Air Pump combines high performance output with quiet operation. It has a single outlet and is ideal for aquariums up to 20 litres (5.5 U.S. gallons).