This button can be used to activate a special function that lowers the temperature to its lowest value for a short period of time. This is used to accelerate the freezing process of fresh foods and thus preserve their original qualities. As soon as they reach their frozen state, the temperature can be returned to normal by pressing the button again. If, however, you should forget, the freezer will automatically revert to the ideal temperature after a short time.
The freezers temperature is constantly monitored: a buzzer sounds when the internal temperature increases beyond the optimal conditions for preserving your food.