Base layers aren't just for cool weather. The Sugoi RS Base Layer Top is designed to work in conjunction with perspiration to keep your body temperature regulated. Sugoi used Icefil fabric to construct the RS top. As the name implies, it features built in technology to keep you from overheating. This means it uses your own sweat to cool your body, in much the same manner that an evaporative cooler works. Additionally, it's treated with Xylitol. Yes, the same ingredient that is used to give gum its minty, tingly taste is used to produce a cooling effect when your body heats up. The Sugoi RS Base Layer Top Sleeveless Women's is available in five sizes from X Small to X Large and in the color White.