Hard-coat + Photochromatic (Changable)

Photochromatic lenses are lenses that stay transparent indoors, but darken when exposed to ultraviolet light from the sun. Essentially, they provide the benefits of glasses and sunglasses in a single frame. A hard coating is a clear film applied to the lens surface that makes it much more scratch resistant. It shouldn’t be considered as anti-scratch, as it will protect the lens surface from minor abrasions such as when cleaning the lens with a tissue.