The D4-20001 / 20002 from Crane Aerospace & Electronics is a Directional Coupler with Frequency 1 to 100 MHz, Coupling 20.25 dB, Coupling Variation ±0.25 dB, Directivity 20 dB, Average Power 3 W. Tags: Flatpack. More details for D4-20001 / 20002 can be seen below.