You don’t need heavy layers to be warm. This microfibre shirt is perfect for lightweight layering at any time of the year. It is made with HeatFX, an innovative combination of fibres that provides superior warmth and comfort without bulk. The fabric has specially engineered pockets inside the fibres to create a thermal warming effect next to your skin. This base layer features: moisture management to keep you dry, spandex for stretch comfort, and heat retention. Fabric: 41% polyester/33% acrylic/23% Viloft viscose/3% spandex. Sizes S - XL.