The EHEIM professional 4+ – our best external filter but now with an integrated 'emergency' button. Have adopted the many advantages of the professional 3 series – powerful performance, optimal energy efficiency, quiet operation, priming aid, safety hose adapter – also improved the technology by incorporating the new ‘Xtender’ button. Product Features: Premium class external filters with all the advantages of the professional 3 series For aquariums from 120 lt to 600 lt Additional control function (Xtender) to counteract blocked filter media and extend intervals between cleaning Square canister for high stability and large filter volume High flow capacity with low energy consumption Adjustable pump output. High performance ceramic axle guarantees quiet running and durability Integrated self priming aid to initially prime the filter Safety hose adapter can only be removed when the valves are closed Top prefilter effectively traps large dirt particles and allows for longer service intervals. Simple to remove and easy to clean. Individually filter baskets with "Easy Clean"grid Fully equipped with original EHEIM filter media and installation accessories.