This is the perfect blacklight for our Ultraviolet items. It is especially useful in the classroom where mobility without a cord is helpful. Works great with our Glow-Bright Concentrate for glow slime, or with Glo-Germ lotion. The bulb is a 6 inch, 4 watt UV (blacklight) designed to give the maximum illumination. Powered by 4 AA batteries (not included.)