Size Small,Medium only in stock. Yonex Very Cool Clothings are constructed using Xylitol, a natural material that absorbs the heat of perspiration. They also have Ultra-Violet and Infra-Red filtering functions which further help towards keeping you cool as well as safe from harmful effects or the rays. The result? Clothes that keep the body temperature 3 degree Celsius cooler than ordinary Polyester to bring the best performance out of you.