I am looking for a way of marking small boxes (say shoe-boxes) with tags that can be read from a distance (5+ metres). The tags must each have a unique code that does not need to be ever changed. No data is stored on the tag - it is all on a database stored elsewhere and keyed on this unique code.
Ideally, the requisite tag would beep or light up when the user enters its unique code - so that the appropriate box can be quickly found.
I hope I have made myself clear, but feel free to ask for more details if not. I have looked everywhere and have not found what I am looking for.