The BoostSolar Charger, new in 2013 from Eton, is a handy backup battery that gets powered up by the sun then can be used to charge smartphones and tablets while you're off the grid. On one side, the BoostSolar features a 5" solar charger; on the other, a removable 4,000mAh lithium battery. The solar panel can charge the battery in 10 hours, giving the battery enough juice to charge two iPhones from empty to full. When used without a battery, the BoostSolar can charge a mobile device directly under sunlight. Weighing in at less than a pound, with a built-in fastener to attach to a pack, the unit is easy to transport while in the backcountry.