Calibre 400 Series movements have two barrels. Each barrel has a 660 mm mainspring. They are connected in series, not in parallel, which enables the five-day power reserve. This means that the drive always comes from one mainspring only. While they absorb and release energy, however, the two barrels are constantly synchronizing. The movement is wound by turning the rotor counterclockwise. The movement can be wound manually (by hand) with 210 crown rotations (clockwise) until it is fully wound.