Our Most Breathable Training T-Shirt Ever! Due to the success of our Flex-Fit Tees, we\'ve developed Flex-Fit Training T-Shirts: lightweight polyester, breathable back, they\'re the highest-performance product YET! Light, High-Performance Fabric with Breathable Back Panel Dri-Fit Fabric Wicks Sweat Away From The Body Oddballs Branding & Design 100% Polyesters Hand made in Newcastle, UK Fully Sublimated Design Care: Machine wash at 30 degrees Chest size is measured by the circumference of the widest part of your upper torso, below the arms. An accurate measurement is important before ordering. Why not pair it with some of our sports shorts, and make the most of your workout?