Youre putting in the effort and working up a sweat but remain comfortably focused on your training with under armours heatgear coolswitch compression ss t shirtcoolswitchmade for a compression fit from a light mix of polyester and elastane coolswitch is at the core of the performance fabric just as the name suggests its all about keeping you cool and this is achieved by technology inside the t shirt drawing heat away from your body and cooling you skin at the same time a simple concept