May 20, 2013. The TH-21 Series thermistor probes from Omega are constructed with a glass encapsulated thermistor element, which enhances stability and accuracy. With a maximum continuous temperature rating of -80 to 200°C (-112 to 392°F), and intermittent operation to 250°C (482°F), these thermistor sensors can be used in applications previously out of reach of epoxy-coated thermistor sensors. The probes can be ordered in any length, but the company recommends a minimum immersion depth of 1.5″, because short probes run the risk of error due to stem conduction effects. The devices have M12 connectors and are suitable for laboratory, R&D, automation, and automotive applications as well as HVAC, manufacturing, and chemical industries.