Invicta 5105 (Add your watch to the comments below…)
The Sea-Gull caliber ST1902 is a mechanical hand-wound chronograph movement. This caliber is known to be based off of the Venus caliber 175. At one point a legend was circulating around the internet claiming that this series of movements is not only based on Venus calibers, but also manufactured on the same machines. If anyone has actual proof of this claim, please share in the comments below.
This movement is essentially a 2 subdial chronograph. The 6:00 subdial on the caliber ST1902 is often simply listed as a 12 hour subdial, causing confusion about the functionality. This is not a 12 hour totalizer subdial for the chronograph complication. It is a 12 hour hand that matches the main central hour hand.
Is ST1902 the same as ST19?
You may see the caliber number for this movement shortened to just ST19. This is accurate as the base caliber number, but it is not accurate when talking specifically about the ST1902. With ST19XX, the last two digits indicate different versions or complications added to the base ST19 (ST1901).
ST1902 VS TY2902:
As is common with watch calibers of Chinese origin, there is confusion with the caliber number system. The caliber ST1902 is the same as TY1902.
At the time of this post, replacement prices for the Seagull caliber ST1902 were found online for around $110.00 USD.