Mask: Human eyes cannot focus underwater. A mask covers our eyes and nose to let us see clearly underwater. The air space inside the mask lets our eyes focus underwater. Required Features Enclosed Nose: Our nose must be inside the mask so we can adjust for pressure changes. This is why swim goggles cannot be used for scuba diving. Having our nose covered also prevents getting water up our nose. Tempered Glass Window: Plastic windows fogs up and get scratched easily. Regular glass windows are easily broken and break into dangerous jagged, sharp pieces. Tempered Glass Windows are made of toughened safety glass. When broken Tempered Glass breaks into rounded chunks that are less likely to cause injury. Adjustable Mask Strap: Allows us to adjust the strap so the mask stays securely on our face. AQUA LUNG® Quartz 1 Mask Mr. & Mrs. Brown both wear Aqua Lung® Quartz 1 Masks. (Mr. Brown's mask is neon yellow. Mrs. Brown's mask is aqua.) These masks are single-window, silicone masks. Special Quartz 1 Mask Features Translucent, Hypo-Allergenic, High-Grade Silicone Rubber Mask Skirt: Dive Masks were originally made of black rubber. Now most modern Dive Masks are made of silicone rubber. The silicone rubber used in Dive Masks is usually translucent. This allows light to come into the mask from all sides, unlike looking through a dark tube using black rubber masks. Some people are allergic to black rubber and have a red ring around their face were the rubber has touched their skin. Silicone Rubber is hypo-allergenic so people are not allergic to it. Silicone Rubber is softer than black rubber so seals better and is more comfortable. Aqua Lung® uses only high-grade silicone in their Dive Masks. Feathered, Double Edges Mask Skirt: Double edges on the mask skirt lets the mask seal better and is more comfortable. Large Single Window: A Large Single Window gives us a better unobstructed view. Low Volume: A smaller air space inside the dive mask allows it to be cleared of water more easily. Wide Mask Strap: More comfortable and doesn't pull on our hair. Swiveling Mask Strap Buckles: Allows for more comfortable and easier mask strap adjustment. These buckles make putting on the dive mask easier. Quick Release Mask Strap Buckles: Unique buckles that separate at the touch of a button for easy mask removal without getting the mask strap tangled in our hair.