Tesla Men's Thermal Wintergear Compression Baselayer Long Sleeve Top 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.