SmartWool's flat knit sock liner provides a close, lightweight fit to minimize friction and blisters. Features wool on wool WOW technology for greater durability. . Made from 64% merino wool, 34% nylon, 2% elastic. Can be worn alone or under another pair of socks. Ultralight, noncushioned sock provides a close, lightweight fit. Act as your second skin to minimize friction and blisters. Wool on wool construction in the heel maximizes the lifespan of the sock. Wicks moisture away from skin and dries quickly. Flat knit toe seam guarantees comfort. Won't itch or shrink. Smartwool Merino fibers are naturally odor free. Smartwool fibers regulate body temperature to keep you warm in the winter and cool in the summer.