The DDTO-250/550-30 from Shanghai Huaxiang Computer Communication Engineering is a Dual Directional Coupler with Coupling 30 dB, Coupling Variation 1.2 dB, Frequency 250 to 550 MHz, Average Power 500 W, Insertion Loss 0.3 dB. Tags: Module with Connectors. More details for DDTO-250/550-30 can be seen below.