The TUSA M-31 Visio Tri-Ex mask is a revolutionary new 3-window design offering an ultra-wide; panoramic view. This amazingly wide viewing angle is achieved by the incorporation of domed side windows and the significant reduction of frame structure around the lenses, increasing the field of vision by dramatically over traditional masks.The M-31 mask gently conforms to the contours of your face. Constructed with crystal silicone, this mask has been crafted for divers who want a wide front lens combined with a low volume design. Like all TUSA masks, it incorporates a wide range of features to enhance comfort and provide clarity of visio