This portable Blue-tooth base stereo is Callmate's answer to music lovers' need for wireless music any-time, anywhere! In fact it is so easy to use that all it needs is a TF card to be inserted. The card will store music and play whenever needed. It can also be conveniently attached to PC, laptops, mobile phones, etc. with an AUX cable. The Blue-tooth can connect the speaker with two devices at the same time. Callmate BE-13 works on a battery whose power can be monitored via a smartphone. Perfect for parties and long trips!.