As Opposed to a battery it's run by a little solar panel to the watch deal with (the 'Eco Push') and because of 'Atomic Timekeeping' it may assert to become the 'most accurate watch in the world'. If what is occurring in Neuchâtel and Prepare-les-Ouates is something to go by, https://www.watchesworld.com/germanys-top-10-favourite-luxury-watches/