With smart moisture management, The Cool Human Endothermic Cooling Shirt sweat-activated tee represents an advancement in apparel. Using endothermic principles, its state-of-the-art microvesicle delivery system uses xylitol for sweat-activated cooling. It works through a heat-absorbing reaction between your sweat and infused xylitol to truly cool you regardless of the temperature outside. A natural sugar alcohol found in fruit, corn, and birch, xylitol has antimicrobial and antiviral properties. Inactive when the shirt is dry, it triggers when you sweat. Made with a TACTEL and lycra blend fabric, each T-shirt is as strong and durable as nylon yet as soft as cotton and as quick-drying as polyester. Plus, with its super-high 50-gauge knit, the ultra-thin fabric still manages to be strong and dense. So it’s great as a regular tee, an undershirt, or a base layer. Furthermore, because it’s UV protective, this sweat-activated tee is great for all your outdoor activities.