This is the Tusa Freedom Elite Mask Wide Field of View for Scuba Diving Snorkeling Features: Wide field of view single lens Equipped with Freedom Technology 180Adeg Rotational Buckle System Medium-large frame with minimal internal volume Five-position strap angle adjustor for micro-adjustment Round edge skirt 3-D mask strap Freedom Elite has a single lens that offers a clear, wide view to the underwater world. The buckle rotates a full 180 degrees to accommodate varying head sizes for optimum fit. The thin frame and rotation of the buckle allows the mask to be folded into a compact size. TUSA&';s patented 3-D strap is a true three-dimensional design that snugly fits against the head&';s natural curvature. The 3-D strap offers unprecedented comfort and fit unlike standard flat mask straps. Freedom technology is a set of revolutionary features offering superior fit, comfort and increased performance in TUSA masks. Freedom model masks feature a dimpled skirt surface with varied silicone thicknesses and stability ridges in addition to a proprietary low-friction skirt surface on the fitting line. The round edge skirt features a proprietary round edge cross-sectionally shaped skirt. This rounded edge results in a soft fit that suppresses pressure and reduces creasing left on the face. The planar fit, instead of linear fit" silicone skirt maintains great fit and unprecedented comfort. "