Smartwool W Intraknit Thermal Merino Base Layer Pattern CrewFEATURES: Smartwool's slim fit is intended to follow the contours of the body Featuring Intraknit technology: Insulation, articulation, and ventilation are seamlessly integrated to amplify movement and comfort during high intensity activities Merino Sport yarn combines the power of Merino with the durability and fast dry times of polyester Seamlessly knit mesh ventilation designed to keep you dry and comfortable 3D mapping provides maximum mobility