The 850185 is an RTD (Pt100) temperature probe designed for use with Extech's 4-channel datalogging thermometer systems. This probe measures temperatures from -40 to 392°F (-40 to 200°C) and integrates seamlessly with the SDL200 datalogging thermometer, which supports 2-channel RTD (Pt100O) datalogging alongside 6 thermocouple types. The probe enables accurate temperature monitoring with a basic accuracy of ±0.4% reading (±1°C) and 0.1°C resolution, making it suitable for precise temperature measurement and data recording applications. It is commonly used in HVAC systems, refrigeration diagnostics, and industrial process monitoring where reliable RTD temperature sensing is required for data acquisition and analysis.