These Varian (Model NRC 840) ion gauge controllers feature dual thermocouple gauges, 1 to 1x10-8 Torr. The two independent thermocouple gauges allow for pressure measurement in the range of 0.001 to 1 Torr while the ion gauge allows for pressure measurement in the 1x10-3 to 1x10-8 Torr range. The basic unit is comprised of a power supply, electrometer, emission controller and ion gauge meter. These Varian NRC 840 high vacuum ion gauge controllers operate on either 115 or 220 VAC. Ion gauge cable and ion gauge tubes are available but sold separately.