Anti-fog - The independent breathing chamber design effectively prevents the mask from fogging with a dual airflow system, and enjoys a crystal-clear viewing experience. 180 Panoramic View - The snorkeling mask gives you a break-proof safety window and the 186 wide viewing angle gives you a panoramic view of the seabed. Full Face - The snorkel mask eliminates the inconvenience of holding the snorkel in your mouth, allowing you to breathe naturally underwater through your nose and mouth. Action Camera Compatible - Suitable for action cameras, allowing you to capture all the amazing things you see while snorkeling. (excluding camera) MORE COMFORTABLE--The quick adjustment ratcheting mask buckle and soft premium silicone rubber skirt make you more comfortable while diving. How to choose the right size? Close your mouth, measure the distance between eyebrows and chin less than 15cm, recommend S/M size greater than 15cm, recommend L/XL S/M size: inner diameter 17*13CM, outer diameter 23*19CM L/XL size: inner diameter 19*13CM, outer diameter 23*19CM Specification: Material :shatterproof polycarbonate + high quality liquid silicone Package Included: 1x Full face snorkel mask