Axial high-performance fan, cylindrical tube sleeve, flanges on both sides, directly driven. Cylindrical tube made of galvanized sheet steel, enclosing the impeller, flange molded on both sides, hole pattern according to DIN 24155. With external terminal box. Impeller with high-performance characteristics with profiled blades made of plastic, aerodynamically optimized for the application, dynamically balanced. Three-phase squirrel-cage motor, two-speed with star-delta connection, closed design, maintenance-free, sealed, low-noise ball bearings with long-term lubrication.