This stretchy-fit top provides thermal insulation for trail runs, but you can always pull down the zip and roll up the sleeves if your body is generating too much heat and you end of running a little longer than you first thought.Otherwise, you can wear it as a baselayer for activities like skiing or walking the dog in winter.Thermal constructionStretch long-sleeves - able to roll up Half-zip - adds ventilationFabric: 65% polyester, 35% viscoseColour: Khaki