About SmartWool Intraknit Thermal Merino 200 Base Layer Top - Merino Wool, Long Sleeve Closeout. SmartWool's Intraknit Thermal Merino 200 base layer top is made from temperature-regulating and moisture-wicking merino wool blended with stretchy polyester for lightweight comfort and easy layering. Itch-free merino wool is temperature regulating, moisture wicking and odor resistant Blended with polyester and stretch for durability and movement Mesh ventilation zones keep body dry and comfortable Flatlock seams for chafe-free comfort 3D mapping for near custom fit and freedom of movement Slim, layer-friendly fit Base layer weight: Midweight Made in India