perpetual calendar

Is a complication that displays the complete calendar information, including the date, day, month, and leap year. It operates with an automatic adjustment mechanism for months that have 30 or 31 days, as well as the leap year cycle where February has 29 days.

Watches with this complication may include additional features, such as displaying the phases of the moon. The mechanism of the perpetual calendar involves a series of gears, levers, and discs that work together to track time and ensure an accurate display of calendar information.