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 7 blades made of GRP, hub made of galvanized sheet steel, blade position continuously adjustable from the outside when stationary, with high efficiency, balancing quality G 6.3 according to VDI 2060. Three-phase squirrel-cage motor with frequency converter, speed controllable (please specify when ordering!), closed design, maintenance-free, sealed, low-noise ball bearings with long-term lubrication.