Cylindrical air diffuser for supply air and installation as a part of visible round air duct. For use in heating and cooling cases. The length is 750mm in all versions and the diameter varies (only some diameters are manufactured). In the side or the bottom there are openings for air distribution. In each opening there is one adjustable blade plastic, in color black RAL 9005 or white RAL 9010. The maximum number of the openings depends of the diameter of the diffuser. The cylinder is made by galvanized sheet steel or steel sheet painted electrostatically in RAL color. In the end of the diffuser there is metal ring for better equalization of the air in the diffuser.