Under armour heatgear sonic fitted shirt junior boys the under armour heatgear sonic fitted shirt is designed to offer maximum performance during active wear made with a crew neck and short sleeves the shirt is made of a skin tight four way stretch fabric which offers both comfort and flexibility while the flatlock seams reduce irritation it is manufactured with heatgear fabric which wicks sweat away from the body and ventilates to keep the wearer cool and dry and features upf 50 to pro