Goal zero rock out 2 solar rechargeable speaker the rock out 2 solar speaker meets the demands of the pickiest most adventurous audiophile with bluetooth our darkbass tm chamber and solar panel integrated a rock out 2 solar speaker in your backpack ensures a long lasting musical trek features recharge by usb solar run time 10 hours usb recharge time 2 hours durability weatherproof chainable yes ideal for guide 10 switch 8 nomad 7 specifications charge ti