Interactive article explaining how a mechanical watch works.
Congratulations on both the watch and the pending nuptials!
Don't have the SBGX261...but it's on the short list for my next watch. Grand Seiko specs most 9F movements at +/- 10 seconds a year, and a few special releases at +/- 5 seconds per year. But I predict you'll get better than spec, the 9F86 GMT in my SBGN003 runs about +1 second per year.
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