Using the latest in electromagnetic induction technology, this amplification speaker does not require any cables, Bluetooth, or other technical connection. Just place your phone, tablet or music player on top, with your device's speaker near the metal induction area. Optimum playing position will vary from device to device. Charging indicator light glows red when charging, blue when fully charged or in use. Approximate charging time three hours, playback time over five hours. 3W Speaker includes a rechargeable 3.7V lithium-ion battery, on/off power switch and micro USB charging cable.