Best Quality Guranteed. Wirelessly connect up to 2 smartphones or tablets to the speaker and take turns enjoying powerful sound. Take charge 4 to the beach or the pool without worrying about spills or even submersion in water. Bluetooth version:4.2 Amplify your listening experience to epic levels and rock the party perfectly by wirelessly connecting more than 100 connect+ enabled speakers. Battery type Lithium ion Polymer 27Wh (Equivalent to 3.6Volt, 7500mAh). Battery charge time 4 hours (5V/2.3A). Music playtime up to 20 hours (varies by volume level and audio content) Please note* the charge 4 does not include a USB wall adapter.