Whatsit?

[Garabaldi]

Any ideas what his is?

 

[jimmy uk]

cover of some sorts looks pretty modern 40 to 50 years

 

[Monty]

Cover for an electrical connection on a circuit board? Monty

 

[DevilDog812]

its a mercury dime!
oh wait, youre talking about that/ i have no idea

 

[CRUSADER]

if it has a small hole opposite the other, its part of a modern buckle piece

 

[DirtDigler]

I'll start by saying I don't know what it is. That said, it has too much patination to be modern. And too much solid brass to be modern. Looks like the one side is bent near the hole. That leads me to think that it was attached to something, maybe with small pins or tacks. One pin came out and then it was bent back until the other pin came out. Maybe attached to the end of a measuring stick to keep it from splitting? I would venture to say it was attached to something wood because the holes are too small to accommodate bolts or screws.

 

[NOLA_Ken]

How about and end cap for a wooden level?