U.S. Divers Aqua Lung Sport Adult Admiral Silicone Snorkeling Set 2 window mask with expanded top to bottom viewing Hypoallergenic silicone face skirt provides ultimate comfort Pivot mechanism that closes instantly to prevent water from entering accidentally or purposely when submerged Patented mid foot flexion provides easier kicking action and enhanced efficiency through the water The Pivot Flex blade separates from the front of the foot pocket which allows the water to pass through instead of down greatly reducing wasted energy