Patek Philippe - Quantième annuel

This Patek Philippe automatic wristwatch with an annual calendar is the first of its kind. The calendars patented mechanism automatically indicates the 30- and 31-day months on a yearly cycle from the first of March to the end of February. Contrary to traditional perpetual calendars, this calibre 3 1 5 S QA annual calendar comprises a complex mechanism of gear-trains and pinions with a total of 316 parts, more than a complete perpetual calendar. The dial, with its tritium-coated gold Roman numerals and hands, indicates the day, month, 24 hours and, for the first time ever, a self-adjusting digital date. This model breaks with horological tradition by replacing the Roman numeral 1111 with IV*. Featuring three independent correctors to adjust the calendar functions, it has a sapphire case back and crystal and is water-resistant to 25 m.
*A characteristic it shares with the 15th-century astronomical clock at Prague’s city hall