The invention provides an RFID circuit for use with new or pre-existing antitheft tags. An RFID pin replaces the current pin on antitheft tags that retailers already own. The RFID circuit is incorporated into or secured to, the pin structure. By replacing the current pin used on antitheft tags with a low cost RFID pin, existing antitheft tags can be inexpensively upgraded to antitheft tags that are also capable of use as inventory management and/or enhanced theft control devices.