Pocket Humidity/Temperature Pen Pocket sized for quick and reliable measurements at any location, the Extech 44550 pocket humidity/temperature pen features a dual LCD for simultaneous display of relative humidity and temperature (in Celsius or Fahrenheit). Measures humidity from 20 to 90 percent RH and temperature from 14 to 122 degrees F (-10 to 50 degrees C) with ±5 percent RH; ±2-degree F/1-degree C accuracy. Key Features The maximum/minimum functions allow for display of highest and lowest readings for both Temperature and Relative Humidity, while the Clear function key enables you to erase stored Max/Min readings to record new values. What"s in the Box Comes complete with pocket clip, one LR44 button battery, and user guide. Specifications: Humidity: 20 to 90 percent RH (±5 percent RH)Temperature: 14 to 122 degrees F /-10 to 50 degrees CAccuracy: ±5 percent RH; ±2 degrees F, ±1 degree C