The temperature of the soldering tip and the temperature displayed on the display of the soldering station may vary. In order to calibrate the soldering station, the actual temperature of the soldering tip must be measured. The QUICK191AD thermometer measures the temperature using a very sensitive 191-212 sensor. The soldering tip is placed on the sensor plate and a small amount of solder is added for proper heat transfer. The highest measured temperature then remains on the display. There is an automatic shutdown function, the shutdown time can be set. Included in the package are 10pcs of replacement 191-212 sensors, a K-type thermocouple and a calibration sheet from the manufacturer. 9V battery not included.