Smartwool M Intraknit Thermal Merino Base Layer HoodieSmartwools slim fit is intended to follow the contours of the body Featuring Intraknit technology: Insulation, articulation, and ventilation are seamlessly integrated to help with movement and comfort during high intensity activities Seamlessly knit mesh ventilation 3D mapping results in near custom fit and freedom of movement Helmet compatible hood and extended collar Thumbholes at cuffs 70% Merino Wool, 23% Polyester, 6% Elastane, 1% Polyamide