80% Nylon/20% Spandex;Lining: 100% Polyester; UPF 50+ sun protection Elastic closure SUN PROTECTION:Boys swim jammers with UPF 50+ features blocks sun's harmful rays. ADJUSTABLE:The swim shorts has elastic waistband with interior adjustable drawstring for a secure fit. Boys swim shorts,quick-drying,chlorine resistant,moisture-wicking material for a comfortable wear. TECHNOLOGY:Youth jammers are lined with flatlock seams supply smooth and non-chafing. Boys swim team trunks work great for swim team practice,swimming training,playing on the beach or summer club.