This is the outdoor wall clock that maintains its unerring accuracy from the radio clock transmitter in Fort Collins, Colorado. Its 14"-diameter face uses 3 1/2"-high numbers for the hour, allowing you to easily read the time from up to 25' away. Providing accurate time across the entire lower 48 United States, the clock’s radio receiver synchronizes with NIST-F1, the United States’ atomic clock which will never gain or lose a second in 60 million years. A thermometer integrated into the face’s 4- and 5-o’clock positions provides readings in 20-degree increments from -20° F to 120° F (inner ring displays Celsius in 10° increments). An adjacent hygrometer provides the relative humidity in 10% increments from 0-100%. Includes automatic Daylight Saving Time adjustment. One AA battery (required) provides up to a year of accurate timekeeping. 18" Diameter x 3 1/4" D. (5 lbs.)