Counterfeit Detector, Nontoxic, No Leak/Dryout, 1.5 oz., Clear Easy-to-use Sure 'N Fast Counterfeit Detector detects counterfeit bills printed on genuine treasury paper and many other types of paper. Unique formula detects counterfeit ink. Rub on bill. If applicator turns dark, the bill is most likely counterfeit. No-mess, no-leak, nontoxic formula won't dry out and will not damage or mark good bills. Bottle offers more than 1,000 applications.