Well, they are very famous in the world for the polarized lenses are tough against impact and designed to present a non-distorted, glare-free range of vision. Also, they are lightweight, and have contoured designs. First, you should know that they are made in china. Also, this is also the most common and best way which is used to spot the fake ones. Generally speaking, if they are authentic, you will find the label which should be written with the words "made in china". You can buy them at http://www.underarmour.com/shop/us/en/mens/accessories/eyewear. in this place, they have different types which you can choose from. And they can just cost about 100 dollars. Besides, they are UV protected, so they can protect you from the UV rays and sunlight. Anyway, just have a try.