Warning: Ultraviolet light is harmful to eyes. Always wear ultraviolet-filtering goggles when using black lights!. A black light custom-engineered to locate those hidden, dried uric salt crystals- invisible to the naked eye. Locate the hidden urine odor sources and treat the "right" spot with Urine-Off. 6 1/2" x 1 1/2" x 1 1/2", requires 4 AA Batteries (not included).