UV 400 mirror flash coating the lenses are mirror flash coated. which not only limits the amount of light that your eyes are exposed to, but also ensure that no light of wavelength 400 nanometers and below reach your eye. Since light with wavelength below 400 nanometers are the ultra violet light range which can cause damage to the eyes. These means that these glasses give you complete uv protection.UVA, UVB, UVC, blue light or any kind of harmful light you can think of.