Customize your Anon M4 goggles for any condition by adding a spare SONAR lens by ZEISS to your collection. 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. SONAR Smoke (7% VLT) SONAR Silver (6% VLT) Dark Smoke (8% VLT Clear (85% VLT) SONAR Green (23% VLT) SONAR Blue (46% VLT) SONAR Infrared Blue (39% VLT) SONAR Red (14% VLT) SONAR Infrared (57% VLT) SONAR Pink (39% VLT) SONAR Bronze (19% VLT) SONAR Night (77% VLT)