This is a small but useful application that frees you from having to buy expensive equipment and at the same time eliminate the use of charts and complicated explanations of the sub-cooling or super-heat process. It's easy to use and always on your pocket. It will works with R22 or R410a, temperature in Fahrenheit or Celsius and pressure in PSI or Kg/cm2. For sub-cooling select the sub-cooling temperature given by the manufacturer and then update the temperature reading in the liquid line and it will give you the pressure to meet yours selected sub-cooling. For super-heat adjust the temperature in suction line and the reading of the pressure in the low side and the real time super-heat temperature will be displayed.