Keeps your body cool and dry during exercise indoors or in warm conditions. Our proCOOL base layers are 30% lighter than previous seasons and now feature an antimicrobial treatment to prevent fabric odor from setting in. The proCOOL Singlet is a warm weather base layer that combines the latest in fabric technology with our signature fit. A six channeled, hollow fiber polyester filament exponentially increase moisture absorption and the release of warm body heat. A mesh knit creates more air pockets across the surface of the fabric, maximizing ventilation and air to skin contact.