What are performance shirts and why should you get one today? Easy! Nine Line Performance shirts: 1.) Promote cooling comfort and versatility with unique moisture wicking properties that evaporate sweat, eliminating odor-causing bacteria build-up in an active environment. 2.) These Performance shirts are flexible with just the right amount of stretch that moves as you move, made of brushed 100% polyester which protects you from harmful UV rays when fishing, hunting, and outdoor activities!