Over forty years ago Terramar was the first company to introduce silk performance base layer products. Thermasilk is still going strong. The Terramar Men's Thermasilk Jersey Crew offers a natural super soft touch and feel with all the technology you need. The result is a breathable lightweight top that keeps you warm, dry and comfortable for all your outdoor adventures. The tradition continues.ClimaSense Thermoregulation Technology: Keeps you comfortable in all conditions Fast wicking and drying Natural breathability Jersey construction and excellent warmth without weigh Features: Engineered to adjust to your body temperature Inhibits the growth of bacteria that causes odor Natural Breathability Excellent warmth without weight Ultra lightweight (1.0) natural fabric Fabric:100% Pure Silk