Features: Support BT 4.0, the transmission speed is faster and more stable, can effectively reduce the sound quality damage. Compatible with all devices that support BT A2DP protocol, such as mobile phones, tablets or computers. Two mobile phones can be connected simultaneously. Double click the earphone multi-function button to redial the last broadcast number. Powerful 5 volt / 3.6A charger charges quickly. Intelligent Circuit Design protects against over-heat, over-currents, over charge and short circuit. Compact and portable.