The hydrodynamic tube design and two-lung restrictor values promote proper body alignment and ensure swifter movements through the water. The design also promotes stability in the water, increasing each swimmer's confidence. A head strap keeps the snorkel in pace and includes buttons on the back for simple adjustment and release. The DURAFIT Silicone padding has a watertight seal and maintains its shape for years. The one-way purge valve promotes easier breathing. For more advanced cardio training, the snorkel includes cardio training caps. Silicone mouthpiece is removable for cleaning. Replacement Mouthpiece sold separately.