YONEX Very Cool Men's T-Shirt The Yonex Very Cool line-up is the coolest sportswear on the market. Thanks to the cooling effect of Xylitol, a natural material that absorbs the heat of perspiration, Very Cool polo shirts lower body heat by 3c - improving comfort during the heat of play. In addition to the inherent cooling and soothing effect of Xylitol, Very Cool polo shirts have ultraviolet and infrared filltering functions. Helping to reduce heat buil-up during physical activity by intercepting 96% of UV radiation and 81% of IR radiation, Very Cool's mesh material further provides effective ventilation performance.