What is this fixing lug on a collar badge?

[derekx]

I'm intrigued by the back of this AAMC collar badge, and what sort of fitting it may have had. It's a short thin-walled metal tube about 2mm in diameter brazed to the centre of the badge, and it appears to have been wrenched off at some stage as the end is quite ragged. It's bent downwards also.
I have 2 AAMC collars with this type of fitting. Can anyone shed any light on it?
Cheers, Derek