In addition, the system has extra 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. Different frequency sets are available upon request if multiple units are needed at the same location. The package includes the speaker, two handheld microphones, power cord, two 9V batteries, 12VDC adapter (cigarette lighter adapter) and a carrying bag.