This product is designed to go for sports and travel for those design and production, it is the permeability of the external use of good diving cloth material, the internal power amplifier uses a YAMAHA digital chip technology, is a designer speaker specifically designed to support, appropriate the effect of music can be fully reflected, to achieve realistic results. with a charging circuit inside the product also can be directly charged to the product with a USB-powered. is full of a battery can be used continuously 60 hours or so, is the best when traveling outdoor products. If you are interested, please contact me Hui