The JBL Boombox is a portable speaker with a powerful bass sound. The bass sound is produced by 4 active transducers and 2 bass radiators. Thanks to the waterproof casing, you can use the Bluetooth speaker without problems on the beach or by the pool. You can connect up to 2 smartphones to the Boombox via Bluetooth. That means you and a friend can take turns deciding what music will blast from the speaker. When listening to the music at an average volume, the battery lasts up to 24 hours. Is your smartphone's battery dead before the battery of the Boombox is? You can charge your smartphone via the USB port.