The BL-4 from MCLI is a 90 Degree Hybrid Coupler with Frequency 50 to 100 MHz, Insertion Loss 0.6 dB, Isolation 20 dB, Amplitude Balance ±0.6 dB, Phase Balance ±2 Degree. Tags: Module with Connectors, Octave Band. More details for BL-4 can be seen below.