1）The advantages of the 1.499 ①It’s inexpensive, since it’s been around for over 70 years. Optically speaking, it has a good, reasonably smooth refractive surface, and very little distortion at the edges of the lens ②The big advantages of CR39 lenses over previous glass lenses were light weight, and better shatter resistance. The lower weight allowed eyeglass makers to experiment with larger size lenses, since CR39 is much lighter in weight. ③Although CR39 has better shatter resistance than glass lenses, it still can shatter under a strong impact. For this reason, more and more optical professionals are moving to newer lens materials (polycarbonate and others, to be discussed in future posts) that are almost impossible to shatter. ④Far lighter than a glass lens ⑤A proven high quality in a wide range ⑥Exists in all design and value-added treatment ⑦For all wearers looking for a simple, exonomical lens2）Minus and plus semi-finished lenses ①Lenses with different dioptric powers can be made from one semi-finished lens. The curvature of the front and back surfaces indicates whether the lens will have a plus or minus power. ②Semi-finished lens is the raw blank used to produce the most individualized RX lens according to the patient's prescription. Different prescription powers request for different semi-finished lens types or base curves. ③Rather than just the cosmetic quality, semi-finished lenses are more about the inner quality, such as precise and stable parameters, especially for the prevailing freeform lens.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 semi-finished optical lens
Model:	1.499 optical lens
Place of Origin:	Jiangsu, China
Brand:	SETO
Lenses Material:	Resin
Bending	50B/200B/400B/600B/800B
Function	semi-finished
Lenses Color	Clear
Refractive Index:	1.499
Diameter:	70/65
Abbe Value:	58
Specific Gravity:	1.32
Transmittance:	>97%
Coating Choice:	UC/HC/HMC
Coating color	Green