A base layer like no other - the Mapped Heatwave Top by Seirus warms your core while perfectly managing ventilation and perspiration. With the insight of body heat-map studies this base layer merges 3 dynamically complimenting fabrics that deliver warmth where it is most needed, including extra warmth for the lower back and kidneys. As well as ergonomically placed Max Wick for increased breathability in areas where we run hot and Polygiene mesh in highest vent areas. The benefit of these strategically placed materials is perfect comfort, no matter the intensity of your activity. The heat reflective properties of the Seirus exclusive Heatwave material mean you can get the warmth you need in just one base layer, no more piling on so many layers just to go outside.