[Lordstan]

While I am no expert on belts, I would that the belt is almost definitely Fire, or perhaps Police, Dept related. The reason I say this is the cut out around the number 5. It's the shape of a badge. I can't think of any reason a baseball team would have the number cutout shaped like this. I think something more generic, like a star, square, or plain circle could be anything, but a badge is a pretty specific shape.

EDIT: I just went to the NYC Fire Museum website. On page 4 of the search results for "belt" are photos of 3 belts with number loops all shaped with the exact same shield cutout surrounding the number.