Sets itself - Accuracy to a split second. Adjusts itself to the U.S. Atomic Clock in Ft. Collins Colorado. Receiver signals six times daily to set time, day and date automatically. Jumbo LCD display that can be seen from across the room. Ideal for home, offices, etc. Displays digital indoor temperature. Daily calendar is displayed in day and date format thru 2097. Requires 2AA batteries (not included). Time display is 2" and date display is 1 1/4".