Schott glass; nuetral density gray no. Ng-4; anti-reflection coated both sides per mil-c-14806
A transparent item of a predetermined size that permits unobstructed and undistorted view of a desired area. It may include a frame, have reference markings, grid lines and may be heat strengthened and/or tinted. It is generally used where safety, security, and/or the restriction of foreign matter are required, such as the visual examination of the inside of pressurized tanks, liquid sights, controlled liquid flow, and inspection of equipment enclosed in a housing. See window (as modified); scale, cathode ray tube; scale, plotting; window, metal; window, wood; and window panel, aircraft.
Classification: Pressed or molded glass articles, wired or not, for building or construction;leaded glass windows etc; formed multicellular or foam glass
NSN 5835-01-268-1924
NSN 5998-00-597-7175
NSN 6135-01-243-5797
NSN 2925-00-233-5644
NSN 5985-01-425-7314
NSN 5999-01-485-2449
NSN 5915-01-260-4112
NSN 5930-01-201-7478
NSN 6105-01-614-7419
NSN 6240-01-270-5998
NSN 5996-00-598-4839
NSN 6620-01-245-0184