This is the router to antenna connection cable for cellular routers that have CRC9 antenna ports and antennas that have a SMA male plugs.  

For MIMO configuration which gives faster cellular data speeds, you will need 2 of these cables. A MIMO antenna or 2 antennas which are mounted at 90 degrees axis from each other on a 45 degree axis from vertical.

Most modems can also just use a SISO configuration using 1 of these cables and 1 antenna plugged into the master port, but the data speeds won't be as fast with a SISO configuration compared to a MIMO antenna configuration.