LuckyStone Handheld Uv Light Torch with Led Flashlight, Portable Money Detector Stamp Detection of Fluorescent Marks, Certificates, Repairs, 6" L, Black Portable black light can be used to detect invisible ink, find pet stains or perform similar tasks Contains 4-watt bulb, emits long-wave ultraviolet light at 365 nanometers Attached strap can be looped around hand or wrist for carrying Measures 6.5" long and 1.6" wide Requires 4aa batteries(not included)