1）How do photochromic lenses work?      Photochromic lenses work the way they do because the molecules that are responsible for the darkening of the lenses are activated by the ultraviolet radiation in sunlight. UV rays can penetrate clouds, which is why photochromic lenses are capable of darkening on cloudy days. Direct sunlight is not required for them to work.      Photochromic lenses work via a chemical reaction in the lenses. They are made with trace amounts of silver chloride. When silver chloride is exposed to ultraviolet light, the silver molecules gain an electron from the chloride to become silver metal. This gives the lens the ability to absorb visible light, turning darker in the process.2) The function of photochromic blue lenses      Light rays on the blue end of the light spectrum have shorter wavelengths and more energy. In and of itself, blue light is natural and can even be healthy when consumed properly.      However, our computer screens, smartphone screens, tablet screens, and even modern television screens use blue light to project their content, and we tend to watch that content in low-light conditions (usually in bed, shortly before sleep). Doing so disrupts the body’s biological clock, giving us less sleep and causing numerous other problems related to not letting our eyes and brain rest at the end of the day.      Photochromic blue cut lenses that are designed not only to be clear (or almost entirely clear) indoors, and to automatically darken in outdoor, bright conditions but also reduce the stress and glare from blue light-emitting devices, especially in low-light conditions. For people who have to work nights or in dark environments but need to look at their screen, these photochromic blue cut lenses allow them to use their eyes while protecting them from the worst symptoms.3） What is the difference between HC, HMC and SHC？

Hard coating	AR coating/Hard multi coating	Super hydrophobic coating
makes the uncoated lens hard and increases the abrasion resistance	increases the transmittance of the lens and reduces surface reflections	makes the lens waterproof, antistatic, anti slip and oil resistance

1.67 photochromic blue block optical lens
Model:	1.67 optical lens
Place of Origin:	Jiangsu, China
Brand:	SETO
Lenses Material:	Resin
Lenses Color	Clear
Refractive Index:	1.67
Diameter:	65/70 /75mm
Function	Photochromic&Blue Block
Abbe Value:	32
Specific Gravity:	1.35
Coating Choice:	SHMC
Coating color	Green
Power Range:	Sph:0.00 ~-12.00; +0.25 ~ +6.00; Cyl:0.00~ -4.00