Ivation Swim Snorkel - Swimming with Adjustable Head Strap, One-Way Purge Valve & Center Mount Mouthpiece Design Adjustable Head Strap Keeps Snorkel in Place Regardless of What Stroke Youre Performing Center Mount Mouthpiece Design Enables You to Keep Your Head Underwater Comfortably One-Way Purge Valve Prevents Water Return, Reduces Discomfort and Eases Breathing Soft, Gentle Silicone Mouthpiece Fits Pleasantly and Provides Excellent Grip for Security Low-Profile Hydrodynamic Tube Design Decreases Resistance so You Can Swim Longer