Highly effective and inexpensive tool for detecting bad bills. Simply make a small mark on U.S. currency. Chemically sensitive ink works instantly. An amber mark passes the test, while a dark brown or black mark fails, meaning the bill is likely counterfeit. Works on all new design U.S. currency (bills series 1959 and later). Dual-Detector with UV LED Cap鈥擴ltraviolet LED is highly effective on U.S. and most international currencies, passports, credit cards, cashier’s checks and money orders. Currency: USD & Most International Currencies; Number of Methods: 2; Counterfeit Verification Methods: Chemical/Ink; Ultraviolet (UV); Ink Color (Legitimate): Amber.