For all Dogfish microfiber shirts we choose the best shirt blanks we can. They are 100% polyester, quick dry, light weight, and uv resistant. All shirts are 30+UPF while darker colors will be 50+UPF. Throw the hood on to protect your neck and ears, or throw the hood on with a hat for less glasses glare and more sun protection. Once you wear one of these shirts you'll never wear a cotton shirt in the heat again.