Men's ClimateSmart Compression Base Layer Shirt and Pant Set Shirt size measured by chest: S:(34-36") M:(38-40") L:(42-44") XL:(46-48") Tagless Long sleeve crew neck and matching pant are made with 86% Polyester and 14% Spandex Microfiber performance material controls moisture! Odor control wicking material has the perfect stretch! Perfect for winter activities!