Noob question, HD SDI MAIN

[Seaofdep]

Hi, i have tried to find information or how to on this HD SDI MAIN. It's for a security dome camera project I am piecing  together one part at a time. My thought is the rj45 is for the rj45 to bnc, power cable , but not sure what the other two connections are for. I  was wondering if anyone can help me understand the connections, and what connects to what.