Blue is the colour of light between violet and green on the visible spectrum. Hues of blue include indigo and ultramarine, closer to violet or purple; pure blue, without any mixture of other colors. The wavelength of 450nm laser pointer is a blue laser, the power of such lasers are usually high output, which is our familiar burning laser pointer. 450nm wavelength lasers mainly belong to class 4, The beam of strong blue laser pointer is extremely bright, anti-stray light interference is strong, it is also widely used in astronomy refers to the stars, site measurements, wild adventure, but also for self-defense, is the preferred equipment for astronomy enthusiasts, outdoor enthusiasts.