Can you tell us more about this piece? Is it a thumb screw or something else? Does it unscrew completely, is it easy or hard to screw in?
what is the brass screw in the photograph? It looks like the box has holes near its bottom, did the brass screw come from one of those holes? Does the top lift off of the base with the screws removed?
sorry I only have questions, I can not identify the box.
Larry