Heading out in very cold weather? Wear this thermal shirt to stay comfortably warm during low-intensity exercise. 6.3-oz. fabric has two non-bulky layers. Outer layer contains Merino wool for natural insulation. Inner layer is pure cotton, for softness next to your skin. Together, both layers trap air to create a warm thermal barrier. Close-to-body fit allows for easy layering Details include tag-free banded crewneck and non-chafe flat-locked seams. Great on its own or as base-layer thermal underwear