Several times a day the watch receives the official US government time via a time calibration signal from the atomic transmitter in Ft. Collins, CO, eliminating the worry about changing your watch for Daylight Saving Time. Our atomic watches also feature a perpetual calendar, eliminating the need to adjust your watch for calendar month to month inconsistencies and Leap Year. With the additional features of Tough Solar power, sunrise/sunset data, world time and multiple alarms, you truly will be on time, all the time.