Men's UA ColdGear Fitted Longsleeve Crew Tops by Under Armour polyester Fabric Type: Stretch--Usually a blend of knit or woven fabric with spandex or elastane. Creates a soft, durable fabric which allows freedom of movement yet retains its shape through repeated wash cycles. Performance Technology: Under Armour ColdGear --For when it's cold. ColdGear features a double-sided fabric that wicks moisture from the skin and circulates body heat. It accomplishes the impossible by keeping athletes warm without weighing them down. Anti-Microbial--Anti-microbial treatments provide permanent odor protection by inhibiting the growth of bacteria and mildew in the fabric. UV Protection--Fabric is treated to block UV (ultraviolet) radiation from the sun, helping to prevent sunburn. Ventilation--Mesh or breathable fabric inserts in high heat zones allow sweat to evaporate and cool air to circulate.