Non opening side scuttles for ships, very light type (skylights), with glass holder for fastening with screws
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 02/01/1969

Side scuttles for ships – Extra-lightweight (skylights) – Unopenable, screw-on side scuttles
standard by Deutsches Institut Fur Normung E.V. (German National Standard), 05/01/2016