Protect yourself and your business from accidentally accepting counterfeit money with a counterfeit detector pen from Store Supply Warehouse. Our counterfeit detector pens make it quick and easy to detect fake currency. These pens work on US and Canadian paper bills. Buy one for each register in your store and keep them handy! Store Supply Warehouse carries a wide range of security products including security mirrors, simulated surveillance cameras and more. All Store Security Products are in stock and available for immediate shipment on all orders placed before 3pm.