Periscopes, optical instruments that let users see over or around obstacles, used in vehicles, submarines and trenches.

Military-use periscopes are controlled; provide licences. Optical and photographic goods are fragile and precision-made: pack in individual sleeves with foam, state specifications (focal length, aperture, magnification, resolution), provide CE/FCC/BIS marks for electronic equipment, keep lithium batteries under dangerous goods rules, and expect customs value checks on branded optics.