Cooling Sport Vest Evaporative Cooling (HyperKewl) - this simple and effective technology works by combining water with our HyperKewl Fabric to create garments that gradually release water through evaporation to keep you cool, but comfortable. The Ultra Sport Vest is a pull over style with ventilation mesh panels on the sides. There is a quilted Nylon outer shell and the Hyperkewl fabric inside. The inner Nylon liner will be water repellant. Available in two colors, Blue with Silver or Plain Silver.