RJ12 cable is custom shielded cable that contains wiring for power, an internal coaxial cable for video, and wiring for audio. It is used to connect a REVO RJ12 analog camera to an RJ12 channel on a REVO DVR. RJ12 cable is specially made for video applications, and is not compatible with Ethernet cable. RJ12 couplers can be used to connect short lengths of RJ12 cable together, if desired. RJ12 connections are not inherently weather proof, and must be suitably protected for outdoor installations. 300 feet is the maximum recommended RJ12 cable length. RJ12 cable is used with standard-definition REVO analog cameras and DVRs (DVR5 series, etc.)