Satechi Voombox Travel Portable Bluetooth 4.0 Speaker with 4W Driver & up to 6 Hours of Playtime Splash Resistant (Black) Stream audio wirelessly from any Bluetooth-compatible device. Passive radiator generates impressive bass despite the speakers compact size. Rugged, splash-resistant design is perfect for outdoor activities and travel. Up to 6 hours of playback with built-in rechargeable Li-ion battery. Built-in microphone for hands-free calls.