I found this article to be a great review of Invicta 9937

I have owned the Invicta 9937OB for about 9 months now and I am generally pleased with the good quality of this Rolex Submariner tribute watch. The following comments are based on my research, experience and opinions about this watch. The OB in the model number stands for "old bezel." This is the coin-edge bezel that Invicta produced prior to their adoption of the scalloped bezel used in many of their present diver's watch models. Personally I prefer the coin-edge bezel, as it is easier to grip and turn than the scalloped bezel Invictas. This watch has a Sellita SW200, Swiss made, automatic movement--a copy of the proven and reliable ETA 2824-2 Swiss automatic movement. The Sellita SW200 is a 26-jewel movement where as the ETA 2824-2 movement has 25 jewels. I've read that Sellita put in the extra jewel to be different (marketing reasons) and claims the extra jewel increases the power reserve of the movement. The Sellita appears to be a good copy of the ETA according to my research.

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