The 4018-20 from Narda-MITEQ is a Directional Coupler with Frequency 18 to 40 GHz, Coupling 20 dB, Coupling Variation ±1.25 dB, Frequency Sensitivity ±0.8 dB, Directivity 12 dB. Tags: Module with Connectors. More details for 4018-20 can be seen below.