The aerodynamic pressure drop is low and the slats are mounted so that they do not allow raindrops to enter. Constructed of special aluminum profiles. Grille is fixed to the frame with reamers and hinges thus allowing easy opening for revision and filter replacement. They are installed onto building elements, directly on the air duct, or via a plenum box. The air flow rate of single ventilation grille can be from 100m3/h up to over 1000m3/h (27l/s – over 278l/s).