For two effective tests in one device, this counterfeit detector pen combines a powerful UV LED light with the dependable Dri Mark Counterfeit Detector Pen for dual protection against counterfeit U.S. currency. The UV light reveals the glowing security threat embedded in U.S. denominations of $5 and up, while the trusted pen detector authenticates U.S. currency paper. With this superior protection against all forms of counterfeit bills, this fast and effective pen is perfect for detecting bleached bills.