As a detective, you always need the right tools when you are on the hunt for evidence or reading secret messages. Ultraviolet light helps you uncover many hidden clues. Exchange top secret info with your friends and fellow agents using this high-tech device. The pen uses a special ink that only becomes visible under ultraviolet light, like the one emitted by the flashlight on its opposite end. You can also use the UV light to find other objects and materials that glow.