Grand Seiko 56GS 5646-7010
56GS was the last generation of vintage Grand Seiko. Right after Seiko issued the 61GS, there was a need to build the ultimate daily watch that could be used for decades, so there were some majors changes. In order to improve robustness and stability, the frequency of the movement was adjusted to 28800bph from 61GS's 36000bph. The movement was also redesigned to be thin and compact, making 56GS the slimmest automatic Grand Seiko at that time. The date could be switched between English and Japanese Kanji, and it could be quick-set by turning the crown.
Year: Aug 1970
Diameter (excluding the crown): 36mm
Caliber: Original Cal.5646A automatic movement
Accessories: Watch only
Service History: Unknown