Made with a curved visor and elastic sweatband, the Tinfoil Hat ergonomically follows the line of your head for all-day comfort. New Era 's 39THIRTY design makes this Oakley cap extra durable and destined for the big leagues, as evidenced by the iconic metal ellipse on the front. Features Authentic New Era 39Thirty design offers durability and comfort. Reinforced front. Flatlock seams. Non-adjustable size. Composition: 97% Cotton, 3% Polyester. Technologies Hydrolix Stay cool, dry and comfortable with our moisture-wicking, wicking system and fast-drying times. Oakley's exclusive O Hydrolix moisture management system protects you during any performance.