This lightweight, form-fitting, stretch thermal shirt is perfect for all highly active outdoor adventures. It is stretch, odor-resistant, moisture-wicking and quick-drying.  Model: 98 Color: Black Temperature: Cold to Very Cold Activity: Medium to High Activity 96% CPT performance polyester, 4% spandex CPT powered by SILVDUR™ technology 6.25-ounce, single-layer engineering Controls odor and inhibits bacterial growth on fabric Wicks and aids in moisture evaporation Athletic fit Shirt Sizing: Small (34-36 inch chest), Medium (38-40), Large (42-44), XL (46-48), XXL (50-52) NOTE: Once thermal underwear is opened it cannot be returned or exchanged, so if you are unsure of a size, please ask.