Hi
I think that this is a top bar for a patriotic association type brooch, usually linked to female family members. I have one that has "30th Infantry" but I can't recall for the present what the main part has on it.
I've also seen examples that have 3 or 4 of these bars, linked together (like a St John's medal for which "year bars" were issued to show that the holder was current) no doubt to show which units the wider family were serving with.
When I locate my example, I'll post a photo and maybe learn more about my own piece!
