Goal Zero Rock Out 2 portable speaker. Amped up sound, toned down size for presentations, excursions and impromptu dance parties. The Rock Out 2 Portable Speaker amplifies tunes from your MP3, phone or laptop for over 20 hours without draining battery power from your device. Darkbass Technology: innovative chamber delivers precise, high-quality sound every time. Water resistant shell stores and protects gear. Bungee harness for easy attachment. Charge anywhere, anytime: juice up the internal lithium battery in 3 hours from USB or sun (using a Nomad Solar Panel - sold separately). Works with any device with 3.5mm jack (Exterior controls optimized for Apple and Windows products and works on most Android devices). Imported.