1.56 flat-top bifocal optical lens
Model:	1.56 optical lens
Place of Origin:	Jiangsu, China
Brand:	SETO
Lenses Material:	Resin
Function	Flat-top bifocal
Lenses Color	Clear
Refractive Index:	1.56
Diameter:	70mm
Abbe Value:	34.7
Specific Gravity:	1.27
Transmittance:	>97%
Coating Choice:	HC/HMC/SHMC
Coating color	Green
Power Range:	Sph: -2.00~+3.00  Add: +1.00~+3.00

3.What is the flat Top 28 Bifocal lens?  A flat top 28 lens offers correction for both near and far distance. It is a multifocal lens commonly prescribed for those suffering from both presbyopia and hypermetropia, a condition whereby, with age, the eye exhibits a progressively diminished ability to focus on near and far objects. The flat top lens includes a segment at the lower half of the lens with a prescription for reading (near distance). The width of the flat top 28 bifocal is 28mm wide at the top of the bifocal and looks like the Letter D turned 90 degrees. Because the flat top bifocal is one of the easiest multifocal lenses to adapt to, it is one of the most popular bifocal lenses in the world. It's distinct "jump" from distance to near vision gives wearers two well-demarcated areas of their glasses to use, depending upon the task at hand. The line is obvious because the change in powers is immediate with the advantage being it gives you the widest reading area without having to look too far down the lens. It is also easy to teach someone how to utilize the bifocal in that you simply use the top for distance and the bottom for reading.1.What are the characteristics of bifocals? Features: there are two focal points on a lens, that is, a small lens with different power superimposed on an ordinary lens; Used for patients with presbyopia to see far and near alternately; The upper is the luminosity when looking far (sometimes flat), and the lower light is the luminosity when reading; The distance degree is called upper power and near degree is called lower power,and difference between upper power and lower power is called ADD (added power). According to the shape of the small piece, it can be divided into flat-top bifocal,round-top bifocal and so on. Advantages: presbyopia patients do not need to replace glasses when they see near and far. Disadvantages: jumping phenomenon when looking at the far and near conversion; From the appearance,it is different from ordinary lens.4. 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

2.What is the Segment Widths of bifocal lens? Bifocal lenses are available with one segment widths: 28 mm. The number after the "CT" in the product name indicates the segment width in millimeters.