In the visible spectrum, a wavelength of 635nm for visible light red, very clearly visible. 635nm laser pointers are widely used it to point at the faraway target or stars and sending out the SOS signal anywhere anytime, it is pretty practical and useful for birdwatchers, nature observers, hunters and target shooters. The least expensive laser pen use a deep red laser diode near the 635nm(nanometers) wavelength. Find great deals on HTPOW for 635nm wavelength lasers with the best price and sevices.