Bifocal reading glasses: accommodate for both near and far vision by adding a unique lower lens with add vision value for reading and near vision. Photochromic technology darkens the lens automatically to help you adapt to changing light. Transition bifocal gradient sunglasses readers reading glasses. Photochromic lenses shift from reading glasses indoor to reading sunglasses outdoor, also you can use it as normal photochromic sunglasses,Radiation protection, UV protection. Photochromic gray bifocal reading glasses readers the top part of the lens is clear, while the bottom section is available in your choice of magnification for reading your favorite book, newspaper, or work Transition photochromic gray bifocal reading glasses lens optical glass containing silver halide microcrystals, Phototropy reversible reaction according to the principle, In the sunlight and UV irradiation variable dark, Completely absorb ultraviolet and visible light absorption of neutral，Back to the dark, Can restore the colorless transparent.