The TX4J1 from Sonoma Scientific is a RF & Microwave Isolator with Frequency 400 to 550 MHz, Average Power 0.2 W, Average Power Forward 0.2 W, Insertion Loss 0.5 dB, Isolation 20 dB. Tags: Module with Connectors, Coaxial Isolator. More details for TX4J1 can be seen below.