<p>The housing has an outer diffuser (6) formed from two partial ring sections, which are connected at an outer circumferential surface by a mechanical connecting unit. A holder is formed from multiple bars (14), which are fastened at an inner circumferential surface of the outer diffuser with an end and circumferentially spaced at a distance from each other. The bars are fastened in an edge region of an inflow opening (7). The bars are mounted at a motor flange (16) of a motor housing (17) of an electric motor (9) with another end. An inner diffuser (26) is arranged within the outer diffuser. The outer diffuser is made of plastic.</p>
