Save the world while on your adventures with the Voltaic OffGird USB Solar Backpack. With a sleek all-black design, this backpack comes with a built-in solar panel to recharge your devices. The OffGrid Backpack uses a totally rugged monocrystalline solar panel. It has a total maximum output of 6.15W at 6V. The bag also sports a built-in 4000mAh 15W battery. The solar panel soaks up energy from the sun to fill up the battery. From there, you can plug in and top up any of your USB devices. In addition, you can recharge the battery before you set off using the included micro USB adapter. With the OffGrid Backpack, you need just 3.5 hours of direct sunlight to charge your smartphone and a bit more for your tablet. The exterior of the OffGrid Backpack is complete with UV resistant fabric to withstand the amount of sun exposure.