Shanghai "Shuang Li" 7621's
Shuang = double; Li = Calendar
An upgrade version of 7221's. It carries ss7 movement with quick-set date-day function. Calendar setting method is same as 7221's, you have to push the stem all the way to the end by turning the crown up and down to set both DD calendar.
Both 7221's & 7621's can consider as rare model as it's the first model which had quick-set function. Compare with 7221's, 7621's are even rarer as the Shanghai watch company has no longer introduced any date-day watch untill SS8 is lauched. The probability to get a 7621's is 10 times harder than a 7221's. Becuase of their unstable date setting design. This model ended and replaced by a more stable and lower-tech model SS7 (3 hrs up & down calendar setting).
Rare Early version of Shanghai Day-date watch
The most early day-date model with no model number marked on the back case.
Shanghi 7621 Date-day Calander watch
A 3 step case 7621 day-date calendar
On the back, it says "Stainless steel 7621 901 Day-date Calander "