Interesting and unique military plano convex lens with etched reticle. Lens is 28mm diameter by 150mm focal length by 10mm thick. Reticle is on the flat side and has cross hairs and lots of small lines. See second photo. The military NSN number: 1240006041304. Part # 7689439. Manufactured 1/82. Unused in original military packing. Limited supply.
