“Black” or ultraviolet (UV) light is a type of light wave within a certain fairly broad frequency range. Within that range, there is a specific light frequency that will cause urine to fluoresce as brightly as possible. Urine Off’s LED Light Urine Finders are engineered to produce that specific wavelength of UV light, so they can more easily locate hidden stains than generic black lights.
(note: incandescent/screw-in household bulbs with “black light” coatings generally will NOT fluoresce urine at all).