This is the only handheld laser that produces the maximum legally-allowed power for civil use in the United States, projecting a bright point of green light to over 25,000' (more than five miles). A microprocessor in the pointer is precisely tuned to 4.99 milliwatts, resulting in an electromagnetic cycle of 532 nanometers on the visual light spectrum (bright green) that travels far enough to be seen on the brightest projection screen across the largest auditorium, and it can even be used to point out stars in the night sky, or be mounted to a telescope to assist aiming. Automatic Power Control technology measures and maintains the beam strength at a constant level, allowing you to leave the laser on as long as desired, unlike lesser laser pointers that fade and deteriorate if left on longer than two minutes. For uncompromised power, the pointer runs on a special 3-volt lithium battery that tolerates cooler temperatures (typical of nighttime astronomical observation) that normally speeds energy drain of ordinary AAA batteries. 4 3/4" L x 1" Diam. (2 oz.)