The DDTO-4-20 from Shanghai Huaxiang Computer Communication Engineering is a Dual Directional Coupler with Coupling 20 dB, Frequency 110 MHz to 2 GHz, Average Power 500 W, Insertion Loss 0.8 dB, Directivity 22 dB. Tags: Module with Connectors. More details for DDTO-4-20 can be seen below.