Depending upon your particular situation, visible stain detection may be preferable to ultraviolet detection. Visible stain thief detection powder is used to trap thieves by applying to objects likely to be stolen. After the protected item comes in contact with the skin, the body's amino acids react with the powder, creating a highly visible purple stain which can last up to several days. Note: the stains may discolor the marked object. Non-toxic. Made in U.S.A.