The SMC-3742 from Sierra Microwave Technology is a RF & Microwave Circulator with Frequency 3.7 to 4.2 GHz, Average Power Reverse 2 to 150 W, Insertion Loss 0.11 dB, Isolation 26 dB, Operating Temperature -20 to 65 Degree C. Tags: Coaxial Circulator. More details for SMC-3742 can be seen below.