As it doesn’t have a yearly calendar it deviates by one whole day every two months, give or take! So you’re off by about 500000 +/- 5 seconds after a year. How one can take it over the Rolex Sky-dweller is beyond me. But it’s an astronomical number of wrong seconds per year indeed if you’re into that. And it’s cheaper, I give you that.I think I'll stick with my Seiko SBGN007. Accurate to +/- 5 sec per year. And a tad more affordable.