The SMC-3748 from Sierra Microwave Technology is a RF & Microwave Circulator with Frequency 3.7 to 4.8 GHz, Average Power Reverse 2 to 150 W, Insertion Loss 0.3 dB, Isolation 20 dB, Operating Temperature -20 to 65 Degree C. Tags: Coaxial Circulator. More details for SMC-3748 can be seen below.