Where can I find the case number? The case number can be found on the back of the watch, which is 2 series of characters. The first series is 4 characters long then separated with a dash, followed by the second series (e.g., U600-S076226). Related articles Where can I find the model number? How do I register my new watch? Where can I find the case number? When should I register my watch? How do I set my watch?