The reason is to show the details of the craftsmanship. The reason why the Omega skeleton movement has no engraving is to show the precision structure and craftsmanship details of the movement. The back cover of authentic watches contains the brand logo, movement model, series name, limited edition number and other relevant information. The plywood or pendulum inside the movement is on the back cover. Marked with the appropriate trademark placard, the movement is securely seated in the case assembly.