Wireless digital thermometer. Easy-to-read display. Water-resistant sensor. Indoor and outdoor temperature display with fahrenheit and celsius. Main unit uses 2 "AAA" batteries, not included. Dimensions: Main unit 2-3/4" W. x 2-1/2" H. x 3/4" D., and sensor - 2" W. x 2-1/2" H. x 1" D.