Thermometrics RL Series of NTC Type Cryogenic Thermistor Probes are used in liquid level detection in various cryogenic liquids. For use in the range of 25°C/77°F (room temperature) to -196°C/-320.8°F (the boiling point of Liquid Nitrogen). Cryogenic thermistor probes consist of a pressed disc thermistor attached to #27 AWG silver lead wires. These units are very stable and exhibit no hysteresis effects. Rapid temperature cycling from 77°F to -320.8°F (25°C to -196°C) has no measurable effect on electrical, thermal or mechanical properties. These units are well-suited for cryogenic control applications, such as liquid level in the 77°F to -320.8°F (25°C to -196°C) range. They may be used at temperatures below the Nitrogen Point with suitable instrumentation.