I did not look up the U numbers on these two little exchange types. The one on the left has a nice gold/yellow glaze. It has small reflective 'flakes' in the glaze. This one looks like an oldie. It has file marks on the base. The one on the right has an outstanding sandy tan glaze with smaller dark brown spots. A really, really pretty glaze! It has a glazed pin hole, and is made of dry process porcelain.