Special Features:

Lusterless black paint on front surface except for a 0.500 in. By 0.625 in. Centrally located rectangle. Three 0.140 dia. Mtg holes csunk 82 degrees to 0.250 dia, equally spaced on a 1.656 in. Bolt circle dia.

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.