This Seagull caliber 3600K was found in an Invicta watch. This movement is reportedly the same as the Tianjin caliber ST36. Tianjin and Seagull are the same company (Tianjin Seagull Watch Group), but they have offices in Tianjin, China as well as Hong Kong. Apparently the different caliber numbers correspond with where the movements ship out of. You’ll notice no engravings or inscriptions on the movement or rotor. Not even a jewel count.