Greetings Mojjax, Are you familiar with the concept of the "night watchman". The night watchman kept watch in or around a building or factory. He walked a route, station to station that required him to trigger a time stamp at each station. He had his own dedicated key that fit one of several holes in the timeclock. As he walked his route he left a record of being there by activating the timeclock with his key. This was likely a fob that went with his key which might be the one under the "Makin Bacon" fob. That key may not be unique enough because they were so complex that no one could have copied it readily.
Similar to what 'Reanm8er' said, back in the day......railroad 'bulls' (police) would walk a prescribed route at night to deter 'hobos' from jumping on the trains in the yard. At certain intervals they would 'clock in' (turn the key) to show where they were and at what time (no sleeping on that job).
Don........
Designed in 1911 for William H. Woolverton, president of American Railway Supply Co., the building’s earliest products were brass baggage checks, lapel tags and badges for the booming US railroad industry. American Railway Supply Building
strike that about the tool check, this site says it is a time check called
brassing in and brassing out,by hanging the check with employee #,
so the timekeeper knows when employee worked
[SIZE=+2][FONT="]T[/FONT][/SIZE][SIZE=+0][FONT="]he[/FONT][/SIZE][SIZE=+2][FONT="]A[/FONT][/SIZE][SIZE=+0][FONT="]merican[/FONT][/SIZE][SIZE=+2][FONT="]R[/FONT][/SIZE][SIZE=+0][FONT="]ailway[/FONT][/SIZE][SIZE=+2][FONT="]S[/FONT][/SIZE][SIZE=+0][FONT="]upply[/FONT][/SIZE][SIZE=+2][FONT="]C[/FONT][/SIZE][SIZE=+0][FONT="]ompany was founded in New York in 1891 and lasted well into the 1920s.
There's your timeframe.
Don....[/FONT][/SIZE]