This is the Agilent Varian FRG-700 Active Full Range Pirani and Inverted Magnetron tool for ignition. This is the 3mm cylindrical pin required to adjust the HV potentiometer to recalibrate the gauge.

The FRG-700 gauge is factory-calibrated. If used under different climatic conditions, through extreme temperatures, aging or contamination, and after exchanging the sensor, the characteristic curve can be offset and readjustment may become necessary.

The cold cathode measuring circuit, which is dominant for low pressures (<1×10-3 mbar), is factory-calibrated and cannot be adjusted. By way of contrast, the Pirani measuring circuit can be adjusted. Any adjustment has a negligible effect on the pressure range between approx. 10-2 mbar and 102 mbar.