Seagull ST3621

The ST3621 is a handwound mechanical movement manufactured by Seagull in China. It is based on the ETA 6498 architecture and includes a small seconds subdial at 6:00 with Incabloc shock protection. The movement is part of the ST36 family and is also known as TY3621, with some indication that ST and TY variants may come from different Seagull factories. It offers an affordable alternative to Swiss movements and is relatively straightforward to service, though factory technical documentation is limited and parts availability can be challenging.