Fastrack is a very well known brand manufacturing watches, sunglasses and a lot more stuff.
I personally visited the kolkata showroom last month. I bought one pair of their aviator sunglasses and ordered for poly carbonate lenses. Fastrack had replacement guaranty on poly carbonate lenses . If your broke the lenses within a period of one year, . they would provide you with a replacement.Unfortunately one of the lenses of my sunglasses broke within one month . When I claimed for the replacement, they told me that they did not have the supply of that particular lenses and could not give me a replacement.Therefor I do not recommend this