This Thermasilk Long-Sleeve Crew Shirt is made from 100% pure filament jersey silk fabric, the perfect combination of luxurious feel, durability, and weight. Warm and soft, but extremely lightweight, this 75g silk fabric has the highest ratio of warmth to weight of any fiber, natural or synthetic, making the Thermasilk Shirt a great base layer. ec2 Qwik-Dri Thermoregulation Comfort Technology keeps you dry by accelerating sweat evaporation, while the antimicrobial fabric resist odor. All natural insulator is sustainable and renewable. Machine washable and dryable. Highly packable for easy travel. UPF rating 15+. Long-Sleeve Shirt has crew neck, saddle shoulders, and ribbed spandex trim. Natural.