The SmartWool Men's PhD Ultra Light Shirt is an airy cool accomplice for crushing personal records on your daily run. This lightweight running top features a sleeveless design and breathable side panels for a well ventilated feel. The merino wool blend actively pulls perspiration off your skin to promote evaporative cooling. Another key benefit to merino wool lies in its ability to prevent the growth of odor causing microbes. Ultimately, this means it'll stay fresher than pure polyester training tops, even during grueling runs and races.