The JIC3700T4200FS1 from JQL Electronics is a RF & Microwave Isolator with Frequency 3.7 to 4.2 GHz, Average Power Forward 30 W, Average Power Reverse 10 W, Insertion Loss 0.3 dB, Isolation 20 dB. Tags: Module with Connector, Coaxial Isolator. More details for JIC3700T4200FS1 can be seen below.