The Smartwool® Kids Classic Thermal Merino Base Layer Crew is made of 100% responsibly sourced Merino wool with an interlock knit to help your little ones stay comfortable on snow days and activities in the mountains. With a flatlock seam construction designed to minimize chafing, a crew neck built with set-in long sleeves, and all of the benefits of Merino, this kids' base layer will help them enjoy winter more.