A/20K-INW-2.5"-BB - 20K Ohms @ 77 Deg F (25 Deg C).  The metal bell box no well configuration has a NEMA 3R rating and is designed for wet environments. It has male 1/2" NPT threads and the sensing element is double encapsulated to avoid sensor failures caused by moisture infiltration.  ACI also standardizes with etched Teflon lead wires and wells must be ordered separately for this part. ACI immersion temperature sensors are designed for HVAC Building Automation System and light industrial applications. Specific applications include: chiller hot water system tank and boilers. NOTE: Welded thermowells are not intended for moving water or high pressure service. Fluid velocity and wake frequency are primary factors in well failure. Machined thermowells should be used in these types of applications. Negative temperature coeffient double encapsulated sensor NEMA 3R enclosure