New Trent’s PowerPak series of portable lithium-ion polymer battery packs are designed for the trail. The PowerPak + (left) weighs in at 10 ounces and has ribbed, scratch-resistant casing designed to withstand some of the lighter rigors of the trail. For ten dollars more, there’s the PowerPak Xtreme (right), which is an ounce lighter, splash-resistant and can handle falls up to 1.5 meters. Both charge up to two USB devices at a time—that means tablets, smartphones, cameras, etc.—and carry up to six iPhone charges-worth of power. The PowerPak is guaranteed to recharge 500 times, so it’ll last long enough to justify the expense.