The Kestrel 4000 NV measures every environmental condition simply with the press of a button! This unit 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. The US Military relies on the Kestrel NV Weather Meters to remain as tough as their operations.