National Geographic Snorkeler Expedition Two Piece Combo: Tunny 4 Mask and Swordfish Semi National Geographic Snorkeler "Expedition" Masks & Snorkel Set. 100% Silicone , Hypoallergenic mask - Crystal Clear Low Profile Double pane CE Tempered lenses. Frame-Lightweight Delrin and plastic. Clear wide field. Mask Strap-flexible and replaceable with - 3 point hold. Ratchet Quick lock (RQL)- mask strap adjustment Mask Skirt-feathered edge seal. Semi Dry Marlin Snorkel with Splash Guard. Wide Breath tube for comfort and ease of breathing and air displacement. Silicone Mouthpiece (orthodontic design for maximum comfort) Patented "Pinch & Lock" Snorkel Tab; East to attach and secure to your mask