Counterfeit Pen, 6 PackEasily detect fake bills with our easy to use counterfeit bill detector. One swipe is all you need to sort out the fakes.. Gold is good, and black is bad, that's all you need to know! An iodine based solution in the pen will react with the wood base in fake bills and leave a black mark.. Long lasting tip, and quality ink ensures that your pens will last.. Our Guarantee: Nadex manufactures a variety of coin management and money storage, and banking