The IS-58-20 from MCLI is a RF & Microwave Isolator with Frequency 345 to 355 MHz, Average Power Forward 20 W, Insertion Loss 0.3 dB, Isolation 20 dB, Operating Temperature -10 to 60 Degree C. Tags: Module with Connector, Coaxial Isolator. More details for IS-58-20 can be seen below.