We have a set of 2 vintage identical black metal buckles.  I don't believe they were for belts as they are a bit heavy duty in my opinion for belts.  They measure about 2 3/8" x 1 5/8" and will accept a belting of up to 1 5/8" or so (there is a black metal cylinder covering the place where the belt feeds in so the belting would move more freely when fed through).  They are in nice condition with a few minor scratches in the paint.

2 Metal Buckles Black Vintage