laser distance meter sends out a inely focussed pulse of light to the target and detects the reflection, the meter measures the time between those two events, and converts this to a distance.

Measuring Range	0.05 ~ 40m (use target plate for longer range)
Measuring accuracy up to 30m (2σstandard deviation indoors)	±3mm Typical
Minimum Reading	1mm
Laser Class	Class II
Laser Type	635nm, < 1mW
Diameter of Laser Spot (at distance)	6mm at 10m; 30mm at 40m
Auto Power-off	180s
Illumination	Available
Continuous Measurement, Pythagoras Measurement, Plane Area Measurement, Volume Measurement	Available
Addition/Subtraction	Available
Battery life (Type AAA, 2×1.5V)	Up to 5000 Measurements
IP Rating	IP54 Dustproof & Waterproof
Dimension & Weight	110mm x 58mm x 30mm, 140g
Temperature Range:	-25℃~70℃ (Storage) 0℃~ 40℃ (Operation)