Brunton Resync Rechargeable Battery - $139.95

When it comes to USB devices, the Brunton Resync Rechargeable Battery is your go-to choice for portable power you can count on. The rechargeable lithium polymer battery stows 9000 mA of portable power and features high-efficiency ports, making it ideal for power-gobbling USB devices like tablets and e-readers. Plus, the water-resistant construction, rubberized shell, and low weight of just 10 ounces make the Resync a trail-worthy piece of equipment. - $139.95