This nine-bulb LED flashlight emits long wave ultraviolet light at a wavelength of 385 nm. It is powerful enough to make gems and minerals fluoresce even in normal room lighting. It quickly changes the color of our UV detecting beads (UV-AST). Comes with a black filter to block much of the white (visible) light. This flashlight reveals special fluorescent markings on US paper currency $5 or greater, markings on credit cards and security features of driver's licenses. Great for detecting repairs in the home as most glue and caulking compounds fluoresce brightly. Loan it to a student overnight and see what they discover! Made of super sturdy aircraft aluminum, these lights were built for rugged field use by prospectors ... so it will easily stand up to classroom use. The flashlight comes ready to use with 3 AAA batteries and a convenient nylon holder to carry on a belt. (9 cm, 3.5")