Blue LED is based on the wide band gap semiconductors GaN (gallium nitride) and InGaN (indium gallium nitride). It can be added to existing red and green LED to produce the impression of white light, though white LED today rarely uses this principle. In contrast to most light sources, it has many benefits which include high reliablility, long lifespan, high shock and vibration resistant and high luminous flux output. The solid package of this LED can be designed to focus its light instead of an external reflector used in incandescent and fluorescent sources. Moreover, blue LED doesn't contain mercury, unlike fluorescent lamps.It is also has small size and can be used combined with other electrical component such as sensor, dimmers and lighting contral. Besides, there are many popular products that feature Blue LED, for instance, blue LED light panels, blue LED christmas lights, blue LED alarm clocks, as well as acne therapy. They are available as car under-dash kits, micro lights, submersible tea lights for weddings, clamp on lights, dog safety lights and so on. Currently, There is a concern that blue LED is capable of exceeding safe limits of the so-called blue-light hazard as defined in eye safety specifications.