The IS-81 from MCLI is a RF & Microwave Isolator with Frequency 17.7 to 20.2 GHz, Average Power Forward 25 W, Insertion Loss 0.7 dB, Isolation 18 dB, Operating Temperature -54 to 85 Degree C. Tags: Module with Connector, Coaxial Isolator. More details for IS-81 can be seen below.