N200 180mm Optical-Glass Flat Port 65 ~Depth Rated to 40mNauticam optical glass dome ports are finely ground to the highest standard of precision and represent the state of the art in both manufacturing and optical technology. Different size ports are available to support a wide variety of lenses and housing types. Port extensions or adapters may be necessary for some ports and housings. This optical glass flat port has a diameter of 180mm and is part of the N200 port system. Technical Specifications Depth