Additional Features: Frequency range 10 MHz to 18 GHz Excellent SWR for reducing mismatch uncertainty Accurate calibration and traceability to NIST Precision type-N connector as standard The Agilent 8481B, Power Sensor, gives you extremely low SWR and is traceable to the U.S. National Institute of Standards and Technology (NIST). 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.