The windows are available in six sizes, with diameters ranging from 10 mm to 2 in. The sizes are standardized for both metric and English systems. The windows are 1, 2, or 3-mm thick, with a tolerance of ±0.25 mm, and the surfaces are parallel to within 30 arc-sec.

Edmund Industrial Optics Inc.,
101 E. Gloucester Pike, Barrington, NJ 08007,
(800) 363-1992,