1）The Advantages Of the Bifocal Lenses Some presbyopes choose progressive multifocal lenses, which gradually change powers from the top portion to the bottom of the lens, without lines to separate them. However, conventional bifocals offer some advantage over progressive lenses, such as providing wider lenses for computer work and reading compared to progressive lenses. Special purpose bifocals are also available for computer work and other tasks requiring powerful near and intermediate vision. While bifocals work great for tasks like driving and reading, they are limited in their ability to provide clear vision at points in between, such as the distance to a computer monitor. Compared with progressive lens, the advantages of bifocals is that they are dependable and typically less expensive than progressive lenses.2）The Features Of CR39 Lens: ① Using CR39 monomer with stable quality and large quantity production capacity. also available in domestic made monomer CR39 lens production, products welcomed in South America and Asia, also provide HMC and HC service. ②CR39 is actually better optically than Polycarbonate, It tends to tint, and hold tint better than other lens materials. ③Our CR39 products include round-top, flat-top, progressive lens, full white lens and Lenticular lens. flat, thin, light, high transmittance, stable color, and precise design, also supply semi-finished lens. ④With competitive price and stable good quality, Aogang optical always searching for long term business cooperation. ⑤They are very good material for both sunglasses and prescription glasses.
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 |
| 1.499 flat-top bifocal optical lens | |
| Model: | 1.499 optical lens |
| Place of Origin: | Jiangsu, China |
| Brand: | SETO |
| Lenses Material: | Resin |
| Function | Flat-top bifocal |
| Lenses Color | Clear |
| Refractive Index: | 1.499 |
| Diameter: | 70mm |
| Abbe Value: | 58 |
| Specific Gravity: | 1.32 |
| Transmittance: | >97% |
| Coating Choice: | HC/HMC/SHMC |
| Coating color | Green |
| Power Range: | Sph: -2.00~+3.00 Add: +1.00~+3.00 |