FUNCTION The ventilation grille 150 is mounted on the outer wall of the air exhaust system. When the fan stops, the slats close automatically and prevent the entry of cold air and the penetration of dirt, insects and other objects. Due to the ease of movement, the flaps open at very low pressures, which is why they are also called floating flaps. VERSATILE APPLICATION Suitable for extractor hoods, workshops, cellars, tumble dryers and much more. Typical clicking noises should be observed when installing next to living areas. PERFECT CHOICE for hobbyists and professionals. Simple installation with standard tools. Insert the ventilation flap into the ventilation pipe or flexible hose and attach it to the wall with the screws provided. Attach clamping eyelets to the ventilation pipe for optimum fixation. We are technical experts and here for you. If you have any questions or complaints, please contact our customer service directly. Your request will be processed immediately. Technical