Energy-saving, cubic ventilation box with low-loss pipe connection nozzles on the pressure and suction side, including flexible sleeves to prevent structure-borne noise and variably usable housing panels for optimal adaptation to structural conditions. Easy positioning thanks to standard crane hooks. Self-supporting housing frame construction made of aluminum hollow profiles. Double-walled, 20 mm thick side panels made of galvanized sheet steel, sound and heat insulated by lining with non-flammable mineral wool. The housing panels can be replaced as required with accessories such as weather protection grilles and condensate trays. Additional accessories, wall bracket and weather protection roof can be mounted inside and outside for any installation. High-performance radial impeller with backwards curved aluminum blades, directly driven. Vibration-free operation due to dynamic balancing together with the motor in accordance with quality level 6.3 according to DIN ISO 1940 T.1. Driven by energy-saving, speed-controlled EC external rotor motor with protection class IP54 with maximum efficiency. Maintenance-free and interference-free, ball bearings. Integrated electronic temperature monitoring for EC motor and electronics. With an internal potentiometer as standard for setting the control voltage and thus any fan speed between min. and max. speed. Stepless speed control with external potentiometer or stepless speed control with universal control system EUR-EC. Connection via standard terminal box (IP54) on the cable provided.