The 137-304B-dBF-dBR-2-2-2-2 from Narda-ATM is a Waveguide Coupler with Frequency 5.85 to 8.2 GHz, Coupling 3 dB, 6 dB, 10 dB, 20 dB, 30 dB, Directivity 40 dB. Tags: Multihole Coupler, Broadwall Coupler. More details for 137-304B-dBF-dBR-2-2-2-2 can be seen below.