Under Armour AllSeasonGear Reversible Long Sleeve Top Boys Synthetic Fit: Fitted--Close-to-body, contoured fit for maximum performance. Performance Technology: Under Armour AllSeasonGear--Between the extremes. AllSeasonGear is made from radical fabrics that flex with changing weather conditions. Its engineered with UA's Moisture Transport System to deliver core temperature regulation and maximum breathability. 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.