The Mountaineer Classic Edition Crew Socks start with merino wool, a fiber that holds warmth through sweat and rain alike and resists odor in a way a synthetic blend can't match. Smartwool builds that wool into their thickest, warmest cushioning tier, wrapping the whole foot in the kind of padding a full day of elevation gain calls for. This crew sock covers long-distance and backpacking hikes, not an afternoon stroll. What Our Gearhead(R) Experts Are Saying:"I keep one pair drying by the fire, one pair on my feet, and one pair still in the pack for the day mine finally wear through. Three pairs means a hole in the toe on day four of a trip doesn't end the trip."