The DDTO-0.8/3-20 from Shanghai Huaxiang Computer Communication Engineering is a Dual Directional Coupler with Coupling 20 dB, Coupling Variation 1.2 dB, Frequency 800 MHz to 3 GHz, Average Power 500 W, Insertion Loss 0.4 dB. Tags: Module with Connectors. More details for DDTO-0.8/3-20 can be seen below.