External audio input; tour guide system can use transmitter with the original microphone; or other headset microphone or handheld microphone; it also supports external audio input; such as MP3; smartphone. Communicating distance; working distance of the transmission system is 200m/656ft in open area; you don't need to worry out of the range. Detachable battery; wireless tour guide system built in detachable and rechargeable lithium battery; it is easy to replace thebattery; ensuring your full day use. Noise reduction function; the transmission system supports noise reduction mode; you can use it in a noisy environment; no worry about not hearing about the sound. Good sound quality; tour guide system deliver reliable and excellent sound for you; you can count on crisp; clear sound performance; overcome noise and distance issues.