Under Armour TNP Sleeveless Tee Mens Fit: Fitted--Close-to-body, contoured fit for maximum performance. Performance Technology: Under Armour HeatGear --For when it's hot. HeatGear technology wicks perspiration off your skin, rather than absorbing it. It's engineered with UA's Moisture Transport System to deliver core temperature regulation and maximum breathability. 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. Fabric Content: 95% PolyArmour polyester, 5% elastane