This is the Grand Seiko 43999 AKA self-dater circa Jan 1965. Slow beat 18000 bph with chronometer cal. 430, sunburst silver dial with amazing faceted indices. This is the 2nd generation GS followed the 3180 from 1963. The 43999 was the first GS to have a date hence the self-dater name, first GS to be waterproof, and it was also the only GS/SEIKO to have "made in Japan" on dial while most just have "Japan". The gold lion medallion on caseback indicates the Chronometer grade movement of the watch. Later in 1965 the 43999 was renamed to 5722A (57GS) with caliber 5722 but it was essentially the same as cal. 430. And started with 5722B the word Chronometer was forced to be removed from dial as the Swiss claimed that the movement was not certified by a 3rd party but by Seiko themselves. There were total 81,000 pieces of 43999/5722 produced between 1963 and 1965.