The kids' Smartwool Classic Thermal Merino Base Layer Crew Top is crafted from 100% responsibly sourced merino wool, offering natural warmth, effective moisture management, and odor resistance. The interlock knit construction delivers breathable comfort while the slim fit design easily layers under outerwear. It features a crew neck and set-in long sleeves, and the flatlock seam construction reduces chafing for all-day comfort.