The green light laser pointer is fantasic! Under certain amospheric conditions you actually see the laser beam as you point out the stars! The EcGreen Laser Pointer, has a wavelength of 532 nm and output power rated at <5 mW. This laser is a super value and is great for use in bright auditoriums and optics explorations. Operates on 2 AAA batteries which are included and comes in its own sturdy storage case.