The Annual Calendar is a great complication. While a regular mechanical calendar watch needs an adjustment on every month with less than 31 days, the Annual Calendar makes the 30-31 distinction and only needs an adjustment in February. It does not command the high prices of a perpetual calendar, while it is mechanically interesting and hardly less functional. The caliber 8611 is based on the wonderful 8501 and shares the same intricate finishing, including the solid gold rotor.
