[ATOMIC SELF-SET TIME] Automatically adjusts to current time zone selection; Accurate to the Second [DAYLIGHT SAVINGS RESET] Automatically resets twice a year for Daylight Saving time (optional ON/OFF) [MULTIPLE TIME ZONE] 4 selections for Time Zones (Pacific Time, Mountain Time, Central Time, Eastern Time) [EASY-TO-OPERATE] Simple set requires 1 AA (not incl.) alkaline battery [EXTEND BATTERY LIFE] Add longer lasting power with Extra-battery compartment (requires 2 AA (not incl.) additional alkaline batteries) to extend up to 5-years