You don’t need heavy layers to be warm - this microfibre base layer is made with our HeatFX warmth technology for lightweight performance layering. HeatFX's innovative combination of fibres provides superior warmth and comfort without bulking. Specially engineered pockets inside the fibres create a thermal warming effect next to your skin. Coupled with our moisture management system, heat retention and legendary comfort to create a great performance layer. Fabric: 41% polyester/33% acrylic/23% Viloft viscose/3% spandex. Made in Canada. Sizes S - XL.