The Helios FK‑Ü 100/150 is an adapter designed to connect a round pipe of DN 100 mm diameter to a flat duct measuring 150 x 50 mm. It is part of the underfloor duct system made of galvanized steel sheet, specifically engineered for domestic ventilation. This adapter ensures a smooth transition between different duct shapes while maintaining corrosion resistance and supporting efficient air distribution in concealed air duct installations in new buildings.