4-way stretch moisture control/breathable heatwave with integrated spandex for improved stretch, shape, and maximum comfort. ergonomically placed max wick fabric for increased breathability. high-performance power mesh for increased breathablilty at perspiration zones. A thin base layer with ultimate warmth - the Heatwave reversible top harnesses the amazing warming power of Seirus exclusive Heatwave technology. The heat-reflective material amplifies 4-5 degrees while also reflecting 20% of your escaping body heat back to you. With brushed Max Wick next to skin for optimal wicking and ventilation throughout. By maintaining a warm core you increase blood flow, which also helps keep your extremities warm.