For ages 12 to adult Check valve function keeps the intake fresh air Equipped with a one-touch holder for ages 12 to adult snorkel. The check valve allows air and water flow to flow in one direction, allowing for easy drainage of water entering the snorkel. Equipped with a one-touch holder for easy attachment to the mask. The mouthpiece material is made of high quality elastomer that is also used for medical equipment. Safe for sensitive skin. Volume: 4.2 fl oz (120 cc); Total Length: 15.4 inches (392 mm); Pipe Inner Diameter: 0.7 inches (17 mm).