The Rangefinder uses a safe 905 nanometer laser that is safe for human eyes, invisible and meets the standard of Class I, First, calculate the time from lanuch to the returned time after encountering the target object, Second, Multiply the time and the speed of the light together, then divided by 2 to obtain the distance of the target object.

GVDA Telescope Laser Rangefinder Rechargeable LCD Laser Distance Meter 1500M 1000M 800M 600M Range Finder for Golf Hunting Sport: