TFA bel-air wireless thermo hygrometer with ventilation tip. Checking room ambient conditions and outdoor conditions at the same time. Opening or closing the windows will improve the indoor climate. Wireless transmission of outdoor temperature. Indoor temperature and humidity with coloured comfort zones for a healthy room climate. Maximum and minimum function.<p>Temperature range: indoor -10 to +60 degree C, (+14 to +140 degree F), outdoor -40 to +60 degree C (-40 to +140 degree F), Humidity indoor 20 to 95 percent, outdoor 1 to 99 percent. Wall mounting or table standing. 1.5 volts AAA batteries required but not included. Measures 95 mm width by 158 mm height by 20 mm depth. Made in Germany.