Special Features:

Bottom 4.0 mm recessed 7.0 - 7.2 mm; top edge chamfered 45 degrees to depth of 1.5 mm; top and bottom surfaces to be polished and visually clear without scratches; all other edges to be machined but not polished

Properties:

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.