Anon Optics offers an extensive selection of spare goggle lenses in various tints for adapting the men's Anon M4 Goggle to any weather condition. The M4 goggle is unique in that it is the world's first goggle compatible with both cylindrical and toric lenses. This spare lens features toric technology which mimics the curvature of the eye for superior optics, enhanced peripheral vision, and maximized venting for fog-free vision. SONAR by ZEISS technology in this lens means ultimate contrast and clarity, giving you the best possible definition and terrain recognition so you can see more accurately on snow. All Anon lenses feature Integral Clarity Technology anti-fog treatment for crystal clear vision in any condition.