Marketing InformationEach displays down from atmosphere to 10 um (bar graph indication above 25000 um) of vacuum to let you know that your vacuum pump is clean and performing properly. If the sensor gets dirty, simply plug a new sensor into the gauge, run through a quick calibration process and be back on the job within minutes. Seven units of vacuum for confidence. This easy to use gauge shows that air and moisture have been removed from the system. A simple push of a button changes the display readout between 7 units of vacuum.