NIKE Youth Hyperflow Flavor Mouthguard The ultimate mouthguard for oxygen intake is injected with fresh flavors. Best in class flavor injection technology creates unique, delicious flavor combinations to encourage long, consistent use. Patented O-flow breathing channels for maximum oxygen intake to improve athletic performance. Rear drainage channels. 88% EVA/8% polypropylene/4% polyester. Imported. Dual-density EVA construction which enables a more customizable fit while still maintaining the shape of its protective outer wall.