Multi-channeled wireless headphonesNo antenna on headphoneUp to 35 hours of operating time between charges with 12 to 14 hour charge timeSuperb sound quality without wires or interferencePowered by classroom friendly internal NiMH batterySwitchable between 4 frequenciesNote: Adding to an existing 6-person Listening Center Be sure to purchase an additional AC power adapter (W980) and 6-way charging cable. One AC power adapter is capable of only charging up to 6 headphones.