FeaturesDiscreet, totally portable security solution Built-in UV light for easy identification of marked items UV light also effective for checking bank note watermarks Quickly and easily write and view \'secret\' messagesBatteries includedThe Eagle Security Pen with UV Light features a long-life UV pen for invisibly marking items and a built-in LED UV reader for viewing. The Security Pen is ideal for making a mark that is invisible to the naked eye until the built-in UV light (or another UV light) is used over the area. The UV light can also be used to check for watermarks on banknotes and other documents, to invisibly mark documents or banknotes or to write secret messages. Batteries included. Note: This product has been tested for reliability on the banknotes listed on the packaging and we are confident that it is effective. However, we cannot be held liable for any loss or damage resulting from using the product.