The Smartwool Classic Thermal Merino Midweight 250 women’s baselayer sweater offers unparalleled feeling and remarkable performance. This first layer is made of responsibly sourced merino wool that enhances breathability, thermoregulation, and natural odour resistance. It features shoulder inserts and flat seams that help reduce irritation caused by chafing. Add this sweater to your winter wardrobe and feel the difference next time you go skiing, hiking, climbing or biking in cold weather. This garment is part of a layering system that provides comfort and warmth for your outdoor activities. Easy to layer, this base layer enables you to regulate your body temperature by wicking moisture away. This onion layering system is made of three types of clothing. The first layer, worn next-to-skin will provide warmth and quickly move moisture away from your skin. Then, the second layer, is the insulation or fleece, that provides warmth while also dissipating heat during periods of high output. And finally, the third layer, the shell, which is the most weather-protective layer, worn on the outside of all other layers.