These are additional or replacement headphones including a battery for the STEREOMAN ISI 2 without a transmitter, which must be connected to the television and also function as a charging station for the headphones. If you already have a STEREOMAN ISI wireless headphone with If you own a transmitter/charging cradle, you can use these second headphones as additional headphones. It is thus possible for two people to each use their own headphones with individual volume levels to listen to the same TV program on television or to music together.