The UM31QB Visio Tri-Ex mask is a revolutionary 1-window design that offers an ultra-wide 168 degree 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 dramatically over traditional masks. The UM31QB mask gently conforms to the contours of your face. Constructed with pure silicone, this mask has been crafted for divers who want a wide front lens combined with a low volume design. 168 panoramic view through 1 window lens. Patented domed side windows. Reduced frame structure to reduce blind spots. Patented round edge skirt for increased comfort and better seal. Three-dimensional strap for unprecedented fit. Five-position strap angle adjustor for micro-adjustment. Pure silicone FDA regulation compliant. ClearVU Tempered. EZ Strap and Buckle System. Mask Fitting: Adult Medium to Large faces. Comes in a Blister Pack.