N120 180mm Optical-Glass Wide-Angle Dome PortNauticam 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 wide angle port has a diameter of 180mm and is part of the N120 port system. Technical Specifications