The M5 sits between the M4 and M6 with a flat-toric lens shape that combines the expanded peripheral vision of a toric lens with the cleaner, more refined profile of a cylindrical frame. If the M4 is the maximum field of view option and the M6 is the wide cylindrical option, the M5 is for skiers and riders who want a wider peripheral field of view without the full M4 frame footprint. Magna-Tech (R) manages lens changes. Two Perceive lenses ship in the box. MFI (R) seals the face mask to the goggle. Anon M5 MFI Goggles + Perceive Variable Blue Lens | Aqua | Christy Sports