The HP 8481D diode 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 8481D high-sensitivity power sensor measures the average power over its entire -70 to -20 dBm dynamic range which gives you accurate readings even if your test signal is subjected to multi-tone environments, modulated carriers, or carriers with high harmonics. You also get extremely low SWR and it's traceable to the U.S. National Institute of Standards and Technology (NIST). The Agilent 11708A 30 dB attenuator is supplied with 8480 series power sensors with the "D" suffix, for calibration with the power meter 0 dBm, 50 MHz reference.