The C1-A81 from RD Microwaves is a Directional Coupler with Frequency 400 MHz to 2.9 GHz, Coupling 30 dB, Coupling Variation ±1 dB, Directivity 20 to 30 dB, Average Power 500 W. Tags: Module with Connectors. More details for C1-A81 can be seen below.