Smartwool"s heaviest line, Midweight, is perfect for forays into alpine environments where temperatures -- and schedules -- fluctuate. * Comfortable next to the skin, and offering the world"s most efficient moisture-management system. Perfect as a base layer, or stylish on it"s own. * 100% wool interlock knit. Machine wash cold, tumble dry low. * Kid"s Unisex sizes X-Small (chest 24-25, size 5-6) Small (chest 25.5-26.5 size 7-8) Medium (chest 27-28, size 10) Large (chest 28.5-29.5, size 12) X-Large (chest 30-30.5, size 14)