Polarized sunglass
Polarized lenses are made of a synthetic plastic known as CR-39 or polycarbonate. Genuine polarized sunglasses are very expensive than ordinary sunglasses. Many shops sell cheap polarized sunglasses that are nothing but mere replicas of the originals. However, a genuine polarized lens can be tested by rotating it in a particular direction and also seeing if the glare through the lens changes in its intensity on rotation. A fake sunglass may in fact damage eyesight.
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