* Size:65 X 50 mm * Aperture size: 45 X 30 mm Available in 100, 200, 300 and 600 lines per mm.  * The grating is protected by two glass plates 65 x 50 mm and bound together at edges. * Grating area 45 x 30 mm. * Available individually as TE215 * Available as set of four as TE215S