Quickly changing weather conditions require constant, immediate updates. Measure wind speed, temperature, relative humidity, dew point and wet bulb temperature with ONE instrument, the Kestrel 3500NV Weather Meter. Many Kestrel users need to know everything that the weather is doing, but don’t need to log the data. At the press of a button, get all the relevant conditions you need to enable yourself to shift strategies, reduce risk and ensure safety. Note: The Kestrel 3500NV has a night-vision preserving backlight which helps users to sustain natural night vision. The NV's backlight incorporates an optical filter to reduce overall brightness and minimize blue and green spectrum light to preserve night vision. Additionally, NV backlights are also much dimmer than a standard backlight, making it more difficult to detect with the naked eye in night operations. This backlight appears soft greyish pink, not red, and is still in the visible spectrum, so is not compatible with night-vision equipment. It takes 30 to 45 minutes for the average eye to adapt to darkness and maximize night vision. Even a short burst of white, yellow, green or blue light "bleaches out" the rod cell photoreceptors in the eye and causes night blindness until the entire adaptation process can take place again. Light in the red spectrum does not cause this "bleaching out", preventing night blindness and night vision fatigue. Kestrel Weather & Environmental Meters are designed & manufactured in the U. S.A and are backed by our 5-year warranty. Innovatively designed for stability and accuracy in abrupt condition changes. Rugged and durable, Kestrels are drop tested, waterproof and designed to float if dropped in water. Kestrel 3500NV Weather Meter Digital Psychrometer 0835NV