Silent Symphony-Band is an all-in-one wireless headphone system. The transmitter can broadcast audio to wireless headphones within a 300ft. radius. The Silent Symphony can be applied to any situation where a performer or speaker needs to be heard by their audience without the typical amplifier and speaker setup. Simply connect the Silent Symphony transmitter to your audio source, like the main outputs on a mixer or the headphone jack on a smartphone, bands can practice loud without disturbing the others or host a karaoke party in the apartment without disturbing the neighbors. The applications for Silent Symphony are limitless. Each of the Silent Symphony headphone sets is powered by two AAA batteries that last approximately 18hrs.