Each item to be protected is tagged with an RFID anti-theft tag, so those tags can be re-used in many cases.The tag is typically attached by a strong string or a plastic band or by other means (similar to a price tag, sometimes it is the price tag), to the item (say for example an umbrella).

 Now once a shoplifter takes this umbrella and walks to the exit then a large RFID door antennas placed near the exit detect the presence of the tag and sound an alarm.In case of a genuine shopper, if he/she takes the umbrella to the checkout counter, the clerk, after receiving the payment for the item, cuts the plastic band and removes the tag.The umbrella can now be carried by the shopper outside by passing the door antennas without triggering any alarm.The store staff will then typically attach the same tag again to a new umbrella that would be now kept on the store shelf.Alternatively, in case of a disposable tag, the checkout clerk will hold the item near a “tag killer” machine which kills (destroys) the tag by subjecting it to a strong electromagnetic radiation and The tag, then though physically present on the item, will not trigger the alarm while passing through the door antenna field.