The exterior grille of the hood serves as an exterior ventilation grille, covering the ventilation ducts. Comes with wall anchor and screws for installation. This check valve can be used universally on all common round ventilation ducts and flexible pipes up to DN150MM. Stainless steel is weather and corrosion resistant. The functional ventilation grille 150 is installed on the exterior wall of the exhaust system. When the fan stops, the slats close automatically, preventing the entry of cold air and the penetration of dirt, insects and other objects. Due to their ease of movement, the blinds open with very little pressure, which is why they are also called floating blinds. Wide range of uses Suitable for kitchen hoods, workshops, cellars, dryers, etc. Typical clicking noise should be observed when installed near living areas. Perfect choice for hobbyists and professionals. Easy to install using standard tools. Insert the vent cover into the vent duct or pipe and secure it to the wall with the screws provided. Install the clamp grommets on the vent pipe for optimal retention. Note: The data is all measured manually, please allow 1-3cm error due to differences in light and display , there may be color differences, please refer to the actual item received.