New old stock. Very sensitive, also detects bluetooth/cellular signals. It can be a challenge finding a 'quiet place' these days (at least in populated areas) where it's not detecting something! One of many vintage items from a computer store that closed abruptly in the early 2000's. Items have been carefully stored since that time- see my other listings for more items, including many in their original packaging! Thank you for stopping by. Have a great day!