With Goal Zero's Rock Out Rechargeable Speaker and the Nomad 3.5 Solar Panel you'll never go without your music! Jam to your favorite tunes for up to 20 hours on a single charge! Sound good? Plug the headphone jack into your mp3 player or laptop and share your music or just rock out by yourself. If you need more sound, daisy-chain several Rock Outs together to amplify your tunes. Recharge your Rock Out speaker by plugging it into the Nomad 3.5's USB port or by any USB port. You can also charge your cellphone from the Nomad 3.5 solar panel in 2-5 hours straight from the sun! This is the perfect kit if you love music!