The EL Series ultraviolet lamps are manufactured with a durable, extruded-design metal housing and scratch resistant powder paint. Basic configuration offers one UV and one white light tube -- the advantage of white light or UV illumination from one unit. Use white light when working with materials in a dimly-lit area. Selected models use two tubes of the same wavelength or the 2UVTM Models use two different wavelengths. The 3UV ModelTM available only in the eight watt lamp gives three wavelengths in one lamp. No other lamp offers this versatility. Easily switch among the three wavelengths (longwave, shortwave and midrange UV) as your application requires.