I don't have this one but I have a polypropelene shirt. It makes a good base layer because polypropelene is "hydro phoebic" meaning it releases water. If you wear a cotton layer above it most of the perspiration will be absorbed into the cotton leaving a dry layer against your skin. Also Polypropelene is a good insulator and is light weight. I have been using an Under Armor type garment made by Nike (because it is cheaper) as a base layer lately as it works in a similiar way. As it gets colder I will go to my poly garment.