The Listen Personal FM System is a good single-user solution for classrooms, worship services or special events where you need added listening capability for an individual. The lightweight transmitter with microphone can be worn or set up on a podium. The receiver and earphone allow a person to sit up to 150 feet away and still hear the speaker clearly without distracting environmental noise. Limited lifetime manufacturer's warranty. Features: Range up to 150 feet LCD display 3-stage battery level indicator on transmitter and receiver UP and DOWN buttons let you easily find a clear channel SEEK button scans channels to pick up an existing FM assistive listening transmission System includes: 1- Portable FM body-pack transmitter 1- Lavalier microphone 1- Personal receiver 1- Ear speaker earphone 1- Soft case to transport system What's the difference between a 72MHz and 216MHz system? FM systems transmit sound via radio waves (generally on 72-76MHz frequencies). They are ideal for classroom/meeting use and work well both indoors and outdoors. If multiple FM systems are used near each other, separate broadcast frequencies should be used. FM signals are not limited to line of sight and can penetrate walls and ceilings. FM and digital systems allow for a range of around 75-150 feet, depending on which unit you purchase and the surrounding environment.. What is an FM system? FM systems transmit sound via radio waves (frequency modulation) from the speaker's microphone to the listener's portable receiver.