Olympus POL-041W Replacement O-Ring for the PT-042 and PT-043 Underwater Housings 180 FULL FACE PANORAMIC VIEWING WINDOW provides a crystal clear, comfortable, and uninterrupted view of the majestic oceanic world. Our fog resistant design allows you to breath naturally and comfortably trough your nose and mouth while snorkeling. With GoPro Mount you can easily attach GoPro Camera to the mask and capture and share your incredible underwater experiences with your loved ones. NEW ADVANCED UNIQUE DRY TOP TECHNOLOGY is designed to automatically lock the top valve to prevent water from entering the mask through the breathing tube. INNOVATIVE DOUBLE AIR FLOW CHANNELS STRUCTURE prevents the fogging of the viewing window via separate inhaling and exhaling channels, making your snorkeling experience free of frustration and full of uninterrupted enjoyment of the beautiful subaquatic scenery. BREAKTHROUGH DOUBLE SEALING TECHNOLOGY uses advanced medical grade, non-toxic, eco-friendly liquid Silicone Pro, that hugs your face snugly preventing any leakage. SATISFACTION GUARANTEED- We hold very high standards for Aqualation equipment, thus providing quality assurance for our customers. In the event of any problems with our mask, we offer an exchange for a brand-new product of 100% refund.