5 Pack Counterfeit Money Detector Pen Banknote Tester Currency Cash Checker Marker Fake Dollar Bill Black This highly effective and inexpensive pen/marker is used for detecting fake bills and deterring counterfeiters from passing fake currency Just simply make a small mark on U.S. currency and the chemically sensitive ink works instantly. The amber colored mark passes the test, while a dark brown or black mark color means the bill is counterfeit 5 Pack Bundle 2 in 1 Black Ballpoint Pen & Counterfeit Money Detector