Smartwool Classic Thermal Merino Base Layer Crew - Women'sSmartwool Classic Thermal Merino Base Layer Crew Women's 2026 Ladies Smartwool Baselayer Top Meet the new and improved Women's Merino 250 Base Layer Crew. We've updated this 100% Merino wool fan favorite with new color options and an enhanced fit to improve functionality while elevating aesthetics. The addition of shoulder panels and its flatlock seam construction helps prevent chafing and increases your comfort level. Add one of our best base layers