^{Note 1} Light Emitting Diodes (LED's)

An LED is a semiconductor chip that converts electrical energy directly into light. An LED is classified as a solid-state light source because it has no gas or liquid components, as do other light sources. The LED's in the MK3 Battle Light consists of an emitter chip mounted on a solid base; the chip is attached to electrical leads that conduct power to it, and it’s encased in a clear polymer that is shaped to focus or disperse the LED's light in the desired manner.

LED's generally emit light within a narrow spectral band. In order to produce white light, which consists of nearly the entire visible spectrum combined, LED's that emit near-ultraviolet blue light that strikes an upper layer of phosphors are used. These phosphors absorb the blue light and re-emit white light, in much the same manner that fluorescent light tubes produce white light.

LED's possess tremendous advantages over incandescent lamps. First, LED's can last thousands of hours versus less than fifty hours for high-output incandescent lamps. Second, because LED's are very robust in construction, and have no delicate parts such as glass bulbs or filaments, they are extremely resistant to vibration and shock, making them well suited for the combat environment or for mounting on firearms. Third, white-light LED's produce virtually no invisible infrared radiation, as opposed to incandescent lamps, which emit over 85% of their output as infrared, and therefore LED's are much more efficient in producing light than incandescent lamps — an important factor for battery-operated flashlights. And fourth, they will emit light over a wide range of power input, making LED's the natural choice for variable-output light sources.

Most LED's emit from a flat surface, necessitating complex reflectors and lenses to produce desirable beam characteristics. Because LED's are susceptible to potential damage from overheating, they have certain thermal design requirements that dictate the maximum output possible from a given LED, and affect the overall configuration of the specific illumination tool. LED's are difficult to manufacture without some variance in lumen output and color. For this reason, they are tested and sorted by the manufacturer.