Vtin Royaler Premium Stereo Bluetooth 4.0 Speaker 20W Output with Aluminum Housing, Passive Radiator, Strong Bass for iPhone, Samsung-Yellow Powered by dual ten watt drivers with a passive radiator, which provides you rich bass. With a rechargeable 5000mAh polymer-Li-ion battery, it is easily to support 8 hours playing time at the volume of 50%. Portable size makes it easy to carry from room to room. With Bluetooth 4.0, it is easy to pair with your Bluetooth-enabled devices. The auxiliary port comes handy if you want to connect your devices that do not have the Bluetooth function. 45 days money-back and 12-month, worry-free Guarantee!