The D4-20003_4 from Crane Aerospace & Electronics is a Bi-Directional Coupler with Frequency 1 to 100 MHz, Coupling 20.25 dB, Coupling Variation ±0.25 dB, Power 3 W, Insertion Loss 0.3 dB. Tags: Module with Connectors. More details for D4-20003_4 can be seen below.