The N9951A from Keysight Technologies is a RF Spectrum Analyzer with Frequency 300 KHz to 44 GHz, Resolution Bandwidth 1 Hz to 5 MHz, DANL -143 to -91 dBm, Attenuation Range 10 dB, Third Order Intercept(TOI) 9.5 to 16 dBm. Tags: Analyzer with Screen. More details for N9951A can be seen below.