Having purchased a freezer supplied without thermometer, I bought this one. The installer told me "let the 3", with this thermometer I know he was right: less than 21 to 19 depending on ambient temperature. Will just think watching the thermometer when you dig in the freezer and remember to change the battery in good time ...... Otherwise the thermometer makes the "job", and indicates the minimum and the maximum recorded (the two small digits to the left of the screen). In short, it is a thermometer that gives the temperature!