is a tool tag.In a shop setting, a worker would go to the tool room and
when he removed the tool he needed he would leave that tag in it's
place so all would know who had that tool.
The number is the workers ID number and often times, it was his pay roll number also.
If the tool didn't show back up, the number was used to ID the worker and charge him for a tool replacement.
Tags without names and only numbers are many times either
cow ear tags, or more often, a miners' payroll number.
A miner would fill a cart with coal, send the cart out of the mine
with his tag hangin on the cart. (they were often paid by the cart)
That way, they knew who filled that particular cart and
could then pay him for it.