Strong performance, optimal energy efficiency, pleasant smoothness, suction aid, safety hose adapter and many other advantages, are adopted from the professionel 3 series. But the highlight is the new "Xtender": if the filter masses are dirty and the water flow decreases, you can simply readjust the flow with the rotary knob. This way you do not have to intervene immediately and gain a few days until the next cleaning of the filter media. The biological filtration (detoxification) is nevertheless maintained by diverted water flow. In terms of colour, the professionel 4+ appears in a new guise. The filter is kept in modern anthracite grey and is supplied with matching hoses, tubes, etc.