The NW3.7G4.2-30-CS-I from NoiseWave is a Noise Source with Frequency 3.7 to 4.2 GHz, Excess Noise Ratio (ENR) 30 to 35 dB, Flatness -/+ 0.75 dB, Temperature Compensation -20 to +75 deg C, Voltage 28 V. More details for NW3.7G4.2-30-CS-I can be seen below.