1) What is photochormice blue block lens？      The photochromic blue cut lenses are optical lenses that darken automatically in response to the sun UV rays and then quickly return to be clear (or nearly clear) when indoors.At the same time, the photochromic blue cut lens can block harmful blue light and let the helpful blue ray to pass through.      Photochromic blue cut lenses offer the same amount of protection as sunglasses, without requiring you to purchase and carry around an extra set of eyewear. The following factors influence the light transmission and darkening speed: type of light, light intensity, exposure time and lens temperature.2) How to make photochromic lenses？      Photochromic lenses can be made by fusing a light-responsive chemical layer onto the surface of almost any plastic optical lens substrate. This is the technology used in Transitions lenses. However, they can also be made by incorporating photochromic properties directly into the lens substrate material. Glass lenses, and some plastic lenses, use this “in mass” technology. It is not as common.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

1.56 photochromic blue block optical lens
Model:	1.56 optical lens
Place of Origin:	Jiangsu, China
Brand:	SETO
Lenses Material:	Resin
Lenses Color	Clear
Refractive Index:	1.56
Diameter:	65/70 mm
Function	Photochromic&Blue Block
Abbe Value:	39
Specific Gravity:	1.17
Coating Choice:	SHMC
Coating color	Green
Power Range:	Sph:0.00 ~-8.00; +0.25 ~ +6.00; Cyl:0.00~ -4.00