Per the front-panel markings: 0.1-1300 MHz, gain 25db, 50 ohm input/output.

Per the Keysight web page: The Keysight 8447D is a low-noise, high gain amplifier used to improve the sensitivity of counters, spectrum analyzers, RF voltmeters, EMI meters, power meters and other devices. They will also increase the maximum power available from a signal generator or sweeper.