Ivation Snorkel Mask Set - Adult Snorkeling Gear - Double Lens Diving Mask & Snorkel w/Dry Top, Lower Purge Valve Double-Lens Mask Offers Superior Facial Proximity for Underwater Exploration Tempered Glass Lenses Resist Scratching & Withstand Deep-Water Pressures Premium Snorkel Features Flexible Silicone Mouthpiece for Comfort & Durability Full Dry Top Prevents Salt Water from Entering Snorkel  Even When Submerged Lower Purge (Blow) Valve Enables Quick Expelling of Any Water from Inside Tube