Blancpain First generation perpetual calendar Ref5395，After being acquired and operated by Biver in 1982, Blancpain launched multiple complex function wristwatches to showcase its strong technological capabilities,

The unique features of the start-up, including the comical face moon phase, double-layer case, and Roman dial needle design, laid the foundation for the appearance of modern Blancpain formal watches.

This first generation perpetual calendar, launched in 1986, imitates the layout of the Audemars Piguet APQP of the same period. It also features three small panels: week, calendar, and month, with the moon phase at 6 o'clock,

No second hand and leap year. The diameter is 34 millimeters and the thickness is only 8.5 millimeters, making it the thinnest perpetual calendar for a long time!