Seiko

The Spring Drive is a watch movement that was developed by Seiko Epson through collaboration with Seiko Instruments and Seiko Holdings. To date, it is the only commercially available wristwatch embedded technology capable of truly creating a continuous mo...  

I have this model since October 2010 in continous use. Since than it has gained 5 seconds. Just amazing! Best Monti

... as always. Thank you! Ken

Thanks also for the extensive write-up on the history and specs, much appreciated!