The Sierra 2 is an ultra compact, lightweight and ergonomically designed night vision monocular-easily handled, stored and transported. The unit features a premium quality 1st generation image intensifier tube, a powerful infrared illuminator, a built-in 1/4"-20 tripod mount for more comfortable longterm observing, a weatherproof body and N-Vision's SLT lens coating technology. The special SLT lens treatment utilizes a blend of metal oxides and fluorides, improving light transition while reducing lens surface reflection.
N-Vision is an understated producer of night vision monocoulars, binoculars & goggles. While others publish specifications claims which favor rare best-case scenarios attempting to gain market share, N-Vision instead prefers to let their products boast by virtue of their own design. They don't list a recognition/viewing range because there isn't a universally applied standard and thus the specification is practically meaningless. They just manufacture high-quality optics, intensifier tubes & housings which perform admirably at a economical price.
There are many different variables that effect the distance that one can see with a night vision device, among them the object's size, the level of details being sought from the object and the conditions of observation. Night vision devices detect much further under a full moon and clear skies than they will under a new moon and cloudy skies. Many different formulas are used to determine the statistic of maximum viewing range and this varies by manufacturer, so ultimately the generation of the intensifier tube is much more relevant than any quoted statistic when determining the maximum viewing range.
All night vision devices sold by B&H have mechanisms in place to protect the intensifier tube from a sudden burst of bright light, but this does not mean that bright light doesn't damage the device. Bright light in any form is not good for the longevity and performance of image intensifier tubes.