Some frames have a series of numbers printed on the inside of a temple arm (the part that goes behind your ear). The first numbers are typically the manufacturer’s style number and color code. But farther down the temple arm, there may be important numbers that refer to the dimensions of the frame. These numbers are the measurement, in millimeters, of the lens width, nose bridge width, and temple arm length. Often the lens width and nose bridge width are 2-digit numbers separated by a square, and the temple arm length is a 3-digit number in front of or behind the others. Knowing these numbers can help you choose a frame similar in size when shopping.

Our 1.50 index lenses are made from CR39, a lightweight and resilient optical polymer that is almost as clear as glass but even lighter. The CR39 provides stellar optical quality and are free on most frames. They can be easily upgraded to include scratch-resistant, UV and anti-glare coating. We recommend this option for people with low prescriptions.

Our 1.57 index lenses are a polymer lens that provides a thinner lens for stronger prescriptions than standard index optical lenses.

Our 1.59 index lenses are made by Polycarbonate which was introduced in the early 1980s in response to a demand for lightweight, impact-resistant lenses 

Our 1.60/1.67/1.74 lenses are made by MR-series, which is premium, clear, strong, thin, with visual appeal and integrity. 

Below is the detail parameter of lenses:

We use free-form lenses (also called digital high-definition lenses) that are leading the industry standard. Our lenses are optimized with computer-controlled surfacing equipment that is much more precise than conventional tools. 

All eyeglasse frames in sllac.com can have tint lenses, including common tint, gradient tint, mirror tint  lenses and polorized lens, so eyeglasses seems the same as sunglasses, is that correct?

No, here are two main difference of sunglasses and eyeglasses:

1. Sunglasses are born for tint lenses, and are more fasion, their seen area are usualy larger and more curved.

2. Sunglasses prescription range is not so wide as eyeglasses.

    current Sllac

    Sunglasses prescription sph range is -6.00 ~ +2.00 ,

    Eyeglasses prescription  sph range is -20.00 ~ +12.00  

this is an approximate range based on the spherical (SPH) value. If you have astigmatism (CYL) in your prescription, this range may be further limited.