Approx.30 x 16 x 15cm, wooden box, 2 chronometers with brass housings, spring chronograph, dials with power reserve indicator, No. 9759, walkable, extremely rare. It is believed that G.U.B. has produced 35 of these double chronometers, which were used to compare the Greenwich time with the star time, and it is assumed that 25 of them were converted into normal ship chronographs and only 10 original ones still exist!