The mechanical calendar watch can automatically distinguish between big and small months and February 28th or 29th. Generally, the year can be calculated, and the simple leap year can be distinguished, which can ensure that the date is always accurate within 100 years (because the general calendar watch can only leap once every four years, not once every hundred years, unless the top calendar watch can do it for more than 400 years), and there is no need to adjust the calendar.

ETA is the world's largest R&D and manufacturer of movement. Swiss brand watches such as Longines, Tudor, Mido, Tissot and Chevrolet all use ETA movement.