Natural Style Round Frame Metal Full Frame Simple Anti-blue Light Glasses

High-concerned chemical : None Element type : Basic Classic Style type : Oval Place Of Origin : China (mainland) Frame Material : Stainless steel Model Number : 1938-3 Gender : Unisex Lenses Material : Polycarbonate Origin : Mainland China The photochromic eyeglasses undergoing a reversible change in color or shade when exposed to light of a particular frequency or intensity.that is , if you test it by hands only , it didn't work . how to test it's photochromic? first : you need a good weather.It means the sun has to reach a certain intensity . second : let the photochromic eyeglasses exposed to the sun fully last: please wait patiently