SmartWool PhD Outdoor Mountaineer

If trekking is hard on socks, then touring is barbarous—which is why we love this new iteration of the PhD. “Some 40 days in these socks, including a bunch of long tours, and there’s no pilling,” one tester raves. Credit SmartWool’s clever construction (debuted in spring 2016) that layers thick, durable fibers in high-wear areas—like the heel, toe, and Achilles—in lieu of a nylon gridding. It allows them to make a sock thin enough to fit in low-volume boots, but strong enough to handle hard use. And they’re comfy: Two different elastics provide greater stretch and recovery. Bonus: The Outdoor Mountaineer has some graduated compression. S-XL