In addition, the system has additional microphone input jack if more microphones are needed. An audio input jack is available so you can play the music using the speaker by plugging in your CD player, cassette player or an MP3 player including ipod. With its versatility and portability, this system has been widely used among the professions such as teachers, auctioneers, studio instructors and etc. We sell to many school teachers, if you or your school already has one, and would like to request buying a different frequency set to prevent interference, please message us the frequency number of your system so we can send you a different one.