Produced between approximately 1933 and 1955, there are dozens of different Bubble Backs. The name « Bubble Back » comes from their extremely rounded, protruding case-backs. This wristwatch is made unique by two main features: its ribbed bezel and its rare dial, both very well preserved. The reeded bezel is highlighted by chased hour markers and finely engraved concentric circles. Contrary to the regular « California dial » with both Arabic and Roman numerals, here they are all Roman.