Comfortable fit for all kinds of work activity, moves with you. No need to be a nerd to appreciate the Advance Cooling Technology of this T-shirt. It's made with hollow filament polyester that traps cool air inside the yarn next to your skin. And unlike the cotton versions that soak up perspiration, this shirt moisture-wicking properties move it away from your body. Mesh side insets keep air circulating for cooler, drier comfort even when it's a scorcher. UPF protection is built in, won't wash out. Material: Polyester.