Speedo Hydroflight Mask/Snorkel/Fin Set Dry top snorkel to keep water out with purge valve at bottom and safety alert whistle New Hydroflight series features our latest underwater innovation for safety comfort and clarity Two window tempered glass mask with watertight silicone skirt and purge valve Speed fit clips for quick easy adjustments Dry top snorkel to keep water out with purge valve at bottom and safety alert whistle Fin system with strong forward propulsion and soft silicone heel straps to prevent chafing