From the site - A wardrobe staple that goes beyond basic, the women's Tech T-shirt wicks moisture and dries quickly to keep you cool and comfortable while hiking, running, working out or throwing a disc at the park. • Polyester fabric wicks moisture away from skin and dries quickly • 2-way stretch provides a comfortable range of motion and a soft feel • bluesign®-certified fabric • Contains materials that meet the bluesign® criteria • REl is Climate Neutral Certified; as we work to actively reduce our footprint, we measure annual carbon emissions and purchase an equivalent amount of verified carbon credits