Ferdinand Berthoud are pursuing the development of their original FB1 tourbillon marine chronometer with the introduction of a regulator version called the FB 1R.6-1. This timepiece is not a simple evolution as the brand had to develop many new components featured in this movement. One of the particularity of this FB 1R.6-1 resides in a very original power reserve mechanism using a special spring solely developed for this timepiece limited to 20 pieces. Additionally to this, particular care has been placed in the material used for the case with a unique steel with super high resistance characteristics.