Sugoi's RS Short Sleeve Base Layer employs a laundry list of tech to keep you cool when the mercury rises. With a next to skin fit, it's able to evacuate moisture in a hurry, to keep you dry. And high tech fabric treatments only enhance the built in cooling. Sugoi built the RS base layer out of its IceFil fabric, which, as the name implies, has a bunch of cooling tech built in, as well as being highly adept at wicking moisture away from your skin. In addition to a UPF 50 UV blocking rating, it's treated with Xylitol. That's right, the same Xylitol that gives mint gum its cool, tingly taste is employed to produce a cooling effect when you're heating up. The RS base layer is designed to fit under a Sugoi pro fit jersey, which means that it's intended to fit snug, without any loose material.The Sugoi RS Base Layer Short Sleeve Men's is available in five sizes, from Small to XX Large, and in the color White.