The DDTO-600/3900-40H from Shanghai Huaxiang Computer Communication Engineering is a Dual Directional Coupler with Coupling 40 dB, Coupling Variation 1.5 dB, Frequency 600 MHz to 3.9 GHz, Average Power 150 W, Insertion Loss 0.9 dB. Tags: Module with Connectors. More details for DDTO-600/3900-40H can be seen below.