The M-31 mask is an ultra-wide panoramic view three-lens mask designed to increase the field of view and improve safety. Conventional three-lens masks have blind spots, but we have reduced the size of these blind spots through the use of domed side windows, creating a wide-angle panoramic view. The front and side windows provide an ultra wide viewing of 168- This mask also features round edge skirt for superior seal and increased comfort and three-dimensional strap that snugly fits against the head"s curvature for unprecedented fit. 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. The 5 Angle Strap Adjustor allows for a five position micro-adjustment on both the left and right sides of the mask. This enables vertical (up/down) and horizontal (left/right) pressure on the face to be delicately adjusted for the optimum fit. TUSA"s Round Edge Skirt features a proprietary round edge cross-sectional 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. You also get a Free Save-A-Dive Kit with your mask.