Our take Merino gets all the attention, but it’s not the only wool around. Kora uses yak wool as well, which is plusher than the sheep-grown variety, to create the comfiest sock we tested. The upside-down construction bolstered fit and feel by minimizing cushioning in the sole in favor of thicker pile on top. This places warmth where you need it most, since your winter boots likely have plenty of midsole insulation. This design kept us cozy on frigid outings and reduced slippage in technical boots during winter ascents. (The blend is 27 percent yak wool, 25 percent merino, and the rest a mix of poly/nylon/elastane.) Tradeoff: A toe seam on the ball of the foot took some getting used to, but no testers reported getting any hot spots or blisters because of it.
Trail cred “The Upside Downs kept my feet from freezing when a snowshoe overnight went a little longer than planned,” said a tester after a trip in Olympic National Park.
$22; 2 oz. (M); XS-XL