Axial high-performance fan with adjustable blades when not in operation, square mounting plate, inlet nozzle, directly driven. Square mounting plate with molded nozzle made of galvanized sheet steel. Impeller with 7 blades made of thermoplastic. High efficiency, low operating noise. Vibration-free operation due to dynamic balancing in accordance with quality level G 6.3 VDI 2060 and DIN ISO 1940. Three-phase squirrel-cage motor, two-speed with star-delta connection, closed design, maintenance-free, sealed, low-noise ball bearings with long-term lubrication.