The Keysight / Agilent / HP 8481B thermocouple power sensor is designed for use with the EPM series, EPM-P series, 70100A, E1416A and the 43x series power meters, and provides extraordinary accuracy and stability. The 8481B power sensor also gives you extremely low SWR. A calibration port is included with the above power meter for calibration with the power sensor. This calibration eliminates the uncertainties due to temperature changes and the variance in making measurements with different meter/sensor combinations.