Under Armour Ventilated Compression Short Long Mens Fit: Compression--Supports your muscles to prevent fatigue during intense training. Fabric Type: Mesh--A knit or woven fabric with small, evenly spaced holes 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.