National Geographic Snorkeler Mouthpiece (Trans Blue) has an orthodontic designed to avoid jaw fatigue. Easy mount snorkel tab to secure snorkel to mask. Wide bore tube for proper air displacement and exchange. Properly sized components to accommodate widest range of snorkelers. Variety of splash guards to keep the snorkel dry under most conditions. The snorkel is designed and should be worn on the left hand side of the mask. This positioned has become the industry norm because SCUBA divers also wear snorkels and the regulator or air delivery system is designed to be placed over the right shoulder. Wearing the snorkel on the left will give you the best results and function out of splash guards at the top of your snorkel as well any purge valve assemblys at the bottom. The snorkel is attached to your mask by attaching the snorkel tab that comes on the snorkel to the mask strap.