Some call it Candy Thermometer. I used this to monitor on the temperature when cooking Water Roux for bread or sugar syrup for French/Italian Meringue or melting sugar in egg white for Swiss Meringue. For example; when boiling sugar syrup, if the temperature is too high the syrup will crystallize. If too low when syrup is pour into the meringue it will turn watery as a result I will waste all my time, effort and ingredients used. I am not a professional baker, with this it really help.