The Fontainemelon 634 watch movement, produced between 1913-1930 with approximately 52,000 units made, features an open face calibre design. It incorporates a bimetallic screw balance with 4 adjustment screws and utilizes a Breguet hairspring. Notably, the movement employs patented big bearings for the crown- and ratchet wheel. Additionally, it includes a barrel with Geneva stopwork. For further details, reference the IWC 52 19'''H5. The movement functions include stem winding and setting, as well as a sub second display.