The SMI-3581 from Sierra Microwave Technology is a RF & Microwave Isolator with Frequency 3.5 to 8.1 GHz, Insertion Loss 0.6 dB, Isolation 17 dB, Operating Temperature 0 to 50 Degree C. Tags: Module with Connector, Coaxial Isolator. More details for SMI-3581 can be seen below.