Dr Cool Men's Short Sleeve Cooling Shirt Constructed using Coolcores patented chemical-free moisture and sweat activated material to make sweat work for you. Delivers three distinct functions: wicking, moisture circulation, and regulated evaporation  to reduce the fabrics surface temperature by up to 30%. Chemical-free (unlike most cooling shirts) so the cooling benefits will last as long as the shirt does. Main body fabric provides UPF 50 sun protection. Main Body Fabric- 88% Polyester 12% Spandex. SHIRT SIZING NOTE: Dr. Cool apparel tends to run a bit on the larger side. Strategically placed mesh inserts for added ventilation & styling; Mesh Inserts:- 90% Polyester 10% Spandex.