While complex ingenuity went into developing the Astérium®, its mechanism and winding device are designed to be simple, intuitive and reliable, as can be seen by merely turning the timepiece over and looking through the transparent sapphire crystal covering the entire movement. It features a host of graduations linked to the astronomic indications through which a single central hand travels. This hand is driven directly by the annual calendar, and therefore performs a complete rotation once every 365.25 days.