Button?

[maccounty]

I believe this is some kind of button, a little bigger than a quarter. Anyone know anything about it?

 

[nhbenz]

Signal Corps collar disk

 

[maccounty]

Thank you nhbenz.

 

[nhbenz]

You’re quite welcome. The link below is a great site for dating such things, I just couldn’t quite see what was or had been on the back. Dating Metallic Insignia: Collar Disks