Ducted radial fan with forward-curved impeller blades, for direct installation in rectangular duct systems. Motor-impeller unit can be swung out. Housing made of galvanized sheet steel with standardized duct flange profiles on both sides, space-saving design, easy to service thanks to the swing-out motor-impeller unit. Forward-curved drum impeller made of galvanized steel, good efficiency, low noise, aerodynamically optimized spiral housing, inflow via nozzle. Impeller-motor unit dynamically balanced. Drive: three-phase external rotor motor, built-in thermal contacts on terminal board, closed design, speed can be controlled using a 5-stage transformer or electronically (continuously) and control using a Helios frequency converter with an all-pole sine filter is possible, winding with moisture protection impregnation, maintenance-free, sealed, low-noise ball bearings with long-term lubrication. Mains connection to pre-assembled terminal box (IP54).