TSLA Men's Thermal Wintergear Compression Baselayer Mock Long Sleeve Shirt YUT32 / YUT42 Winter gear : Thermal Shirts are designed for warmth (Fleece lining). We strongly recommend ordering ONE size up what you normally wear. 87% polyester-13% Spandex. Excellent elasticity with enhanced range of motion. Perfect option during various indoor activities and outdoor excursion. Moisture Sensing/Quick time Dry/TWO-WAY Air Circulation.