Performance Stretch Midweight Polyester Spandex for next to skin comfort with Scent-Factor Technology and Sweat-Powered Cooling. Scent-Factor Technology Performance Stretch Midweight Polyester Spandex Sweat-Powered Cooling ¼ Zip Construction with High Standing Collar Comfortable and Loose Fit Construction Specs 92% Polyester; 8% Spandex Machine wash cold with like colors, Only non-chlorine bleach when needed, Tumble dry low, Remove promptly, Cool iron if needed Sizing and Fit Model is 6'1" and 215lbs. He is wearing a size Large. Fits true size. Here in the office we usually wear one size larger than we do in the guide shirts to allow for layering