The Dri Mark Dual Detector Pen (model DRI351UV6) is a 2-in-1 counterfeit bill detection tool sold in a convenient 6-pack. Each pen combines a chemically sensitive ink marker on one end and a UV penlight on the other, making it ideal for retail environments where counter space is limited.

The ink marker detects counterfeit bills in under a second: simply mark a line on the bill and if the mark turns dark, the bill is suspect. The UV light on the opposite end reveals UV-sensitive security markings embedded in 1996-series or newer U.S. currency denominations greater than $1. The UV light is also effective on many foreign currencies including the Euro, British Pound, Japanese Yen, Swiss Franc, Chinese Yuan, and Hong Kong Dollar, as well as major credit cards, passports, and traveler's checks.

Each pen in the 6-pack includes 3 LR-44 button-cell batteries and 2 adhesive holders with coils for attaching to a cash register or counter. The pens measure 0.8 x 0.8 x 6 inches and are black and green in color. Dri Mark products are made in the USA and hold US Patents 8,406,499 and 8,545,766.