SW-M60 Handheld 60 Meters Laser Distance Meter / Range FInder with LCD Digital Display Size name:60 metres   A laser distance meter emits a pulse of laser at a target. The pulse then reflects off the target and back to the sending device (in this case, a laser distance meter). This "time of flight" principle is based on the fact that laser light travels at a fairly constant speed through the Earth’s atmosphere. Inside the meter, a simple computer quickly calculates the distance to target. This method of distance calculation is capable of measuring the distance from the Earth to the moon within a few centimeters. Laser distance meters may also be referred to as “range finders” or “laser range finders.” Inside the box includes Laser distance meter,power supply AAA,User's Manual,Portable Bag,Portable Bag,Hand Strap,Giftbox,Reflector.