Over forty years ago Terramar was the first company to introduce pure silk performance base layer products. Today, Thermasilk is still the standard for people wanting a natural and breathable garment that is extremely lightweight and will keep you warm, dry and comfortable in all your indoor and outdoor adventures. Low profile design fit great under regular clothes to many any environment warmer. Our Thermasilk Crew provides warmth without bulk and goes great with our Thermasilk Pants.