The Mens Under Armour Heat Gear Flyweight Short Sleeve T-Shirt has a slim athletic fit which delivers better mobility by eliminating the bulk of extra fabric. This t-shirt is ideal for the technical runner. As well as being highly lightweight & having the most breathable fabric, there are also mesh panels for added ventilation. Features Ultra-light, smooth fabric provides extreme comfort & performance Mesh back & underarm panels provide strategic ventilation Signature Moisture Transport System wicks sweat away from the body Anti-Odour technology prevents the growth of odour causing microbes Smooth Flatlock Seams allow a full range of motion without chafing Graphics & logos provide 360 Reflectivity for safer low-light runs Glossary Anti-Odour Keeps gear fresher for longer by preventing the growth of odour microbes. Moisture Transport System USAs signature, sweat wicking technology pushes sweat away from your body to the surface of your gear so it dries faster. Flatlock Seams Lie flat against your skin, eliminating rubbing & chaffing to keep you comfortable & mobile as you work. Reflectivity Reflector elements keep you safe & visible for training at night & in low light.