These Teledyne Hastings hand held portable HPM 4/6 thermocouple vacuum gauge controller are matched for the DV-4 or DV-6 thermocouple vacuum gauge tubes (Stock Number HPM 4/6, Operates on 115 VAC). They measure pressure between the range of 0.01 and 20 Torr with DV-4 and 0.001 to 1 Torr with DV-6. The Teledyne Hastings Digital HPM 4/6 thermocouple controllers are self-contained instruments that offer extreme versatility for most vacuum applications. The electronic design assures long life and minimal maintenance. The compact digital HPM 4/6 has a single switch to operate are battery powered. They are portable and as easy to use in applications where AC power is not readily avaliable. Teledyne Hasting thermocouple tubes are also available but sold separately.