The DDTO-2/4-20 from Shanghai Huaxiang Computer Communication Engineering is a Dual Directional Coupler with Coupling 20 dB, Coupling Variation 1.2 dB, Frequency 2 to 4 GHz, Average Power 300 W, Insertion Loss 0.6 dB. Tags: Module with Connectors. More details for DDTO-2/4-20 can be seen below.