Available only from Hammacher Schlemmer, this is the oversized atomic clock that displays large 5 1/2"-tall digits that can be seen from across a room. It maintains unerring accuracy across the lower 48 states by synchronizing with NIST-F1, the United States’ atomic clock which will never gain or lose a second in 60 million years. The clock also has a temperature and humidity sensor with a 330' range. Includes automatic Daylight Saving Time setting, calendar (day, month, and date), adjustable backlight, and 12/24 hour time format. Mounts to a wall or stands upright. Operates via AC adapter or six AA batteries (not included), sensor requires two AA batteries (not included). 11 3/4" H x 17 1/2" W x 1 1/4" D. (5 lbs.)