Mares offers our distinctive masks so they can be fitted with corrective lenses for near or far-sighted vision. The windows are made from tempered glass and conform to the most stringent international standards (ANSI - DIN). Mares also offers a complete range of positive lenses. These special lenses are applied inside the window of the mask, thereby providing a wide field of vision for underwater exploration and a sharp view of the instruments at the same time. Each mask allows for quick and easy assembly of corrective lenses. The thickness varies as a function of the diopter strengths to always ensure the widest possible field of vision. Negative lenses are available in diopter strengths from -1 to -10, in increments of 0.5. Positive lenses are available in diopter strengths from + 1.5 to +3.