Bc4 retrograde day combines retro design with the functionality of a modern timepiece it is equipped with oris 735 automatic calibre that performs 28 800 vibrations per hour and has 26 bearing jewels a 38 hour power reserve is available for the convenience of the wearer hands and indices are luminous for improved night time visibility a large date window is positioned at 6 oclock while the day display appears at 3 oclock additional useful features include instantaneous day and date day