The quick and simple way to prevent fraud by detecting counterfeit currency. Ink works to react with the starch in wood-based counterfeit paper to leave a dark mark and expose false currency. Just mark a small line on bill and observe results: Amber indicates a genuine bill, while black/dark brown means bill is suspect. Features naturally-occurring, long-lasting antimicrobial technology, which protects against the growth of bacteria on the surface of the pen. For best results, replace cap immediately after use. Reusable adhesive holder sticks to any clean, flat surface to keep pen readily available. Counterfeit Bill Detector Type: Pen; Marking Color: Amber; Counterfeit Indication Mark: Black/Brown.