This air pump is for use with all aquaria from 250 to 600 litres in size. With the external flow control valve included, the TetraTec APS 400 can be easily adjusted to provide the right air flow for all purposes . Innovative design reduces noise while producing high flow. The external flow control valve is included. Exeptional quality and reliability giving a 3 year guarantee.Technical data: high flow due to powerful long-lasting diaphragm, very quiet due to noise supression chambers that absorb sound waves, very quiet operation due to innovative construction of pump, pump output: max: 400 l/h, power consumption: 4,5 W 230 V/50 Hz, for aquaria from 250 to 600 l, number of outputs: 2