The T4XU1 from Sonoma Scientific is a RF & Microwave Isolator with Frequency 3.4 to 4.2 GHz, Average Power 1 W, Average Power Forward 1 W, Insertion Loss 0.25 dB, Isolation 22 dB. Tags: Module with Connectors, Coaxial Isolator. More details for T4XU1 can be seen below.