These Granville Phillips thermocouple gauge tubes are designed for 260, 270, 280, 307 controllers. These thermocouple tube sensors have standard 1/8 inch male NPT vacuum fitting and Granville Phillips part number 270006. They''re the same as DV-6M or DV-6R with 1/8 NPT fitting.Thermocouple sensors (thermal conductivity gauges) rely on the fact that the ability of a gas to conduct heat decreases with pressure. In this type of gauge, a wire filament is heated by running current through it.