Central ventilation box in a compact design, with four exhaust air intake nozzles and one air outlet nozzle. Robust housing made of impact-resistant plastic, light gray. The three intake and air outlet nozzles are designed for pipes of NW 100 and 125 (4 reducers included in delivery). One intake nozzle is designed for pipes of NW 100, 125 and 160 (1 asymmetrical reducer from NW 160 to NW 125 included in delivery). Fan operation in three stages possible using the DSZ operating switch (accessory). Nine speeds are available for individual performance adjustment using DIP switches on the drive electronics. Low-noise radial impeller made of steel in an aerodynamically optimized spiral. Inflow via nozzle. Energy-saving electronically commutated DC external rotor motor with ball bearing for continuous operation. High efficiency even in regular operation. Maintenance-free and free from radio interference.