This is a lovely set of 1969 Czechoslovakia, produced military PNV-57 Night Vision Goggles with adjustable padded Tanker Helmet with head harness in good condition. The helmet is in fair condition with the goggles and battery pack still well-attached. The straps of the helmet appear to be all retained, and the cords appear to be in good condition. The rubber eyecups of the goggles are still intact as well. Not tested, unknown if it works The PNV-57E is designed for night use under natural light conditions from the sky, moon and stars from 0.003-0.005 lux (lux) and higher.Aim of the device: in the army is mainly used for driving cars, amphibians, helicopters, boats. Included in the combat configuration of the Mi24 helicopter, various types of armored vehicles.The operation of the device is based on the amplification of the dim light of the night sky and invisible eye (IR, UV) reflections of road and terrain features and becomes a visible image of the eye. Poor light reflected by road or objects is projected on binocular lenses on the EOPs photocathodes. Photocathodes have a very high sensitivity to light.The image of the photocathode of the tube due to each cathode electron emission becomes an electronic image, which in turn, under the action of a high-voltage electric field, is transferred to the luminescent screen and focuses on it; the electrons that strike the luminescence screen cause it to shine in line with the outline of lens objects perceived by lens optics.In this way, the electronic image is transformed into an EOP image of a visible image that is visible to the observer's eye through the eyepiece.The presence of two tubes in the binocular allows the observer to observe both eyes with natural periscopicity and a normally noticeable depth of perspective. With natural night light levels, much less than 0.003-0.005 lux can be used artificial lighting, creating a luminance that does not exceed 0.003-0.005 lux.Weight 2.3 kgThe field of view of the device is not less than 35 °.Increase 1-1,2xMax. Resolution in the center of the field of view, p / mm, not less than 33Operating resolution in the center of the field of view, p / mm, not less than 26Dioptric shift of the eyepiece, dpt. + 5 / -5Input voltage, V 12-15.5 or 24-30.5Output voltage, kV 19.5The maximum power consumption is not more than 6 WSwitching to 24 and 12 V is done automaticallyThe focal length of the lens is 37 mm, the lens consists of nine lensesTo show the parallelism of the optical axes of the binoculars, a floating connection with the eyepieceIn order to provide a viewer-based installation, the binoculars have a pant device, the base can range from 58 to 74 mm.