The BM13800.4 from Bracke Manufacturing is a Gain Equalizer with Frequency 2 to 18 GHz, Gain Equalization 4 dB, Insertion Loss 1.5 dB, Impedance 50 Ohms, Operating Temperature -55 to 85 Degree C. Tags: Connectorized, Negative Gain Slope. More details for BM13800.4 can be seen below.