The Thor F-2V4A-1D-TxRx is a 2 channel CVBS composite baseband video input 4 channel analog audio transmitter and receiver kit that provides analog baseband composite CVBS video, analog audio, and RS485 serial data over fiber. These units are easy to control via data RS485 and are plug and play optical converters for helping to send video & audio longer distances. Sending Video and audio using copper wires for longer distance than 100 feet is very unpractical. Fiber optic cable, Single-mode or multimode, helps tremendously. There are many cameras or other video devices like VCR, DVD players, Set Top Boxes still using analog Audio/Video interface. This unit has a video BNC 75 ohm interface, for every video there is double the amount of audios which can be used as single-ended or differential-balanced. For example 1 video has 2 audios, 2 videos has 4 audios, essentially you have a video port with left and right audio. In addition, the Transceivers have an RS485 serial Data interface, it allows you to send commands to multiple camera's or other video sources from the headend - receiving location. The kit contains 2 pcs, Transmitter and Receiver, each comes with 12VDC power supply. Tranmitter needs to be located by the Video / Audio source like a camera, the receiver need to be located by the monitor or recording device. Units can be used for timing applications to send CVBS black burst over fiber or sync pulses over fibe