Replica Ray Ban Sunglasses Sale

What are the main differences between cheap sunglasses and expensive sunglasses?

Found that there are eight pieces of the stall, the supermarket has forty pieces, there are one hundred shopping malls, stores have hundreds of thousands of
Is it just that big difference between two lenses? How do you identify this gap?
Cheap sunglasses are dangerous. Why do so many people buy it? Or because this kind of injury is chronic, so do not pay much attention to it?
Attached is a pair of sunglasses from inferior Dads