PURE SILICONE - FDA regulation compliant. (Rubber articles intended for repeated use / 21 CFR 177.2600) TUSA Sport use pure silicone for the snorkel mouth-piece and mask skirt. CLEARVU TEMPERED GLASS lenses provide superior clarity, color, transmission of light and safety over standard glass. EZ STRAP and BUCKLE SYSTEM - Allows masks to be quickly and easily adjusted with minimal effort. Allowing for a precise fit and ease of removal when necessary. HIGH FLOW PURGE VALVE - A large diameter purge valve for simple, quick clearing, reducing the amount of water remaining in the mouth-piece. HYPERDRY SEMI-DRY TOP - Keeps the main snorkel pipe dry by ejecting water through an independent escape pipe.