Caliber 560How it works:The Atmos (Atmospheric Clock) recovers its driving energy from the expansion and contraction of a pressurized can filled with the gas chloroethane when the ambient temperature or air pressure changes. The energy is stored in a pen. According to the manufacturer, 1 ° C temperature difference is sufficient to wind the watch for about 48 hours.Due to the low energy that can be obtained, a torsion pendulum made of the Elinvar metal alloy with a half-oscillation time of 30 seconds is used; the mechanical plant has few parts that can do without oil lubrication. Due to the low available energy, there are no atmos with second hands or chime. On the other hand, because of the slow circulation, it is no problem to run a display of the lunar phases, as is the case with some Atmos models.Also because of the low drive energy, each dust particle would disturb the flow sensitive or bring to a standstill. The works are therefore always glazed. The average achievable accuracy is given with about one minute deviation per month, carefully regulated specimens should deviate less than 30 seconds. It was recommended by the manufacturer in previous years to have an overhaul after 20 years at the latest. The expected lifetime is given as "several hundred years" (source: Wikipedia).The clock works fine.Case: Gilded brass, dimensions (W x D x H): 225 x 155 x 200mmThe watch is delivered without box and documentation.