Berlinlasers Green Laser Pointer with Simple Alkaline Battery
When green laser pointer is manufactured with simple alkaline battery power source, according to very simple insert of 2 pieces of AAA batteries, it can easily get highly bright and visible green laser beam and light spot in distance. Owing to its quite sensitive color green laser beam emitting, even a low power 5mW green laser pointer can get highly visible laser beam as long as 2 kilometers. This green laser pen is just a great dot positioning tool for all astronomy stargazing, research, military targeting, exhibition and entertainment etc.
http://www.berlinlasers.com/5mw-green-laser-pointer