Audiovox FM100A FM Modulator with IST2 Isolation Transformer Description: Audiovox FMM100A Would you like your car video system to play its sound through your factory installed stereo system, rather than setting up a separate sound system for your car video? With the Audiovox RF Modulator FMM100A you can do just that. The Audiovox RF Modulator FMM100A allows the sound from the Video Source to be played through your vehicle's factory stereo. You must wonder how that can be done. Well, it is quite simple. The Audiovox RF Modulator FMM100A connects to your factory Car FM Radio Antenna and makes this possible. The key components to this system include an FM Modulator, RCA Signal cables and turn-on Switch. There is an AUX input too.