Rechargeable devices (headlamps, PLBs, etc.) offer a greener alternative to traditional batteries, but long trips require an additional—and packable—source for topping up. The NB10000 fits the bill: When one ounce-counting tester’s headlamp turned on in his pack on a weekend trip to Badlands National Park, this compact battery saved him from 13 hours of darkness. Weighing in at 5 ounces, it’s about 40 percent lighter than most other 10,000mAh power banks, and it also has both USB and USB-C ports. “I would usually choose to sweat my juice usage instead of adding weight, but this battery was light enough that it didn’t bother me,” our tester says. We found that the NB10000 charged both a GoPro and a headlamp from dead with capacity to spare. We also charged an iPhone X 2.5 times on a separate occasion. It takes about six hours to charge the battery back to 100 percent with a 20-watt solar panel. Don’t be fooled by its sleek exterior: An IPX5 water-resistant rating and a durable, carbon-fiber frame make it trail-friendly.