Black Atomic Contemporary Clock, 16.5" Overall Diameter, Black Case, 1 Aa (sold Separately)Maintains its accuracy by automatically matching the National Bureau of Standards Atomic Clock in Boulder, Colorado and automatically setting itself to daylight saving time. Changing of the hour hand saves maintenance labor in facilities with numerous clocks. Larger dial size makes it easier to tell time from a distance. Slimline design gives sleek, modern appearance. Display Type(s): Analog; Movement Type: Quartz; Time Format: Standard (12 Hour);