Under Armour Flex Jacket Mens Fit: Loose--Generous cut for ultimate comfort and ease of layering. Performance Technology: Under Armour AllSeasonGear--Between the extremes. AllSeasonGear is made from radical fabrics that flex with changing weather conditions. It's engineered with UA's Moisture Transport System to deliver core temperature regulation and maximum breathability. Ventilation--Mesh or breathable fabric inserts in high heat zones allow sweat to evaporate and cool air to circulate. Fabric Content: 100% polyester