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. Once you wear one of these shirts you'll never wear a cotton shirt in the heat again. You can't beat a camo american flag, your favorite tackle shop, and a comfortable microfiber shirt put together.