The Agilent 8481B thermocouple power sensor is designed for use with the EPM series, EPM-P series, 70100A, E1416A and the discontinued 43x power meters, and provides extraordinary accuracy and stability. The 8481B power sensor gives you extremely low SWR and is traceable to the U.S. National Institute of Standards and Technology (NIST). A calibration port is included with the above power meter for calibration with the power sensor. This calibration provides traceability to NIST and it eliminates the uncertainties due to temperature changes and the variance in making measurements with different meter/sensor combinations.