This TP101 electronic digital thermometer is made in pen-type structure for convenient and portable use and made of stainless steel probe which is safer and more durable. Importantly it is available to various measured subjects including liquid,paste,oil,food processing,rubber and plastics processing and so on at a wide range of -50℃~+300℃ （-58℉~+572℉) . 
Specifically you can notice that there is four buttons of the thermometer which are in functions of switching ON/OFF, switching C/F degree, Holding certain temperature and displaying MAX/MIN temperature.
In detail, when you press the button of temperature lock function for the first time, the displayed temperature will be locked but the lock will be removed when you press it again. And when you press the button of displaying MAX/MIN temperature, it will show the previous maximum temperature first and show previous minimum temperature for the second press but for the third press it will recover to the state of measuring temperature.