Know the time to one-millionth of a second the instant you open your eyes! This clock accepts signals from the atomic clock in Fort Collins, Colorado for unparalleled accuracy - it automatically calibrates itself daily & changes for daylight saving time too. Also features indoor temperature, day/date display, 12/24 hour time formats, alarm with snooze, blue backlit display, four time zone settings, adjustable projection arm & more. Approx. 6" x 3-3/4" x 1-1/4". Three AA batteries not included. AC adapter included.