brass lid / buckle

[GTB]

Does anyone have an inkling of what this unidentified small dug brass item could be? It is approx. 1 1/4" x 3/4", die-struck brass and the 4 edges are shaped to form a lid, or perhaps a buckle top??
I am unsure which is the right way up as the logo(?) or even perhaps a cypher or letter, is as yet unidentified. Hoping it may have military connotations, but will be satisfied to just have it given an i.d.

GTB