The ETA 2603 is a manual wind mechanical watch movement commonly referred to as the "Wehrmachtswerk" due to its historical affiliation with the German military. This movement features a sub second function and a date complication that can be set by changing the hours between 22 and 24. It also includes an adjustable stud holder for precise regulation, shock protection to ensure durability, and a calendar. The ETA 2603 was notably used during the period of approximately 1970.