This Smartwool Women's Intraknit™ Thermal Merino Base Layer Crew is a lightweight, super-moveable top, made for all of your most extreme cold-weather activities. With Merino Sport yarns and gender-specific ventilation perfectly placed to maximize thermoregulation and breathability during high-intensity activities, it helps amplify moisture management, movement, and comfort. When you're in our best base layers, you're ready for anything.