When push comes to shove, it's hard to cook at camp without a little bit of plucky bluegrass ricocheting through the Goal Zero Rock Out 2 Speaker. The Rock Out 2 Speaker features the same amplification that you've come to know and love from the Rock Out series, but without draining battery power from your device (be it laptop, phone, or MP3 player). The two 40mm speakers and 3-watt drives deliver a crispy audio experience, while the lithium-ion battery runs for 10 (and then some) hours on a full charge. Additionally, the Rock Out 2 charges via USB charging cord, making your life a shade easier, and the 3. 5mm audio jack input makes for seamless transitions when you need 'em.