The 4151-20 from Narda-MITEQ is a Directional Coupler with Frequency 820 to 980 MHz, Coupling 20 dB, Coupling Variation ±1 dB, Frequency Sensitivity ±0.15 dB, Directivity 25 dB. Tags: Module with Connectors. More details for 4151-20 can be seen below.