This hi-tech tee, is engineered to perform in the toughest conditions where controlling your body temperature is key. The secret 37.5® technology, which uses active particles to vent heat in warm conditions and retain heat if it’s cold. Proven to help athletes perform better. A blend of recycled poly, merino and spandex, it will out perform any other shirt. It's super soft and great looking, so you will enjoy wearing it workout or weekend.