Soundproofed duct radial fan for direct installation in rectangular duct systems, fan unit can be swung out. Housing made of galvanized sheet steel with standardized duct flange profiles on both sides, space-saving design, sound-absorbing inner lining backed with 50mm thick mineral fiber panels. Easy to service thanks to swing-out motor-impeller unit. High-performance radial impeller with backwards-curved blades made of plastic and galvanized steel. Vibration-free operation thanks to dynamic balancing in accordance with quality level G 6.3 DIN ISO 1940 T.1. Drive: three-phase external rotor motor, built-in thermal contacts led out to terminal board, closed design, speed can be regulated 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).