On the right is the best known of the Bochs, The post patent U-928. In the center is the U-928A sometimes refered to as the "Big Boch". On the left is the very scarce pre-patent dry process U-928 with the true raised embossing "BOCH INSULATOR PAT. APL'D FOR" on the shoulder circling the crown. The next two photos show a good glazefill and a very, very poor one.