If you ever need to mark money, radios, plastic baggies or paper items so you can trace them but don't want anyone else to see the markings, try using an Ultraviolet Fluorescent Marking Pen. It will write on most plastics, metals, woods and papers. Write your name, initials, case number, agency code, date or other information that will fit on the object to identify that item as yours. Use it to mark paper currency in drug buys. Mark plastic baggies of narcotics or radios, television sets and weapons used in "sting" operations. It works just like a felt-tip pen and dries almost instantly. View the object under a long wavelength ultraviolet lamp.