With its classical lines, the Villeret collection has been core to Blancpain since the early 1980s. The annual calendar watch indicates the date of the month, automatically taking account of the variation in number of days between the months. Every day towards midnight the hour hand triggers the date indicator via a gear train. The differences in length between the months are taken into account using a cam wheel possessing lobes and notches of varying depths. This secondary date mechanism causes an additional jump when the month has 30 days.