Kazbec - Matte Blk/smoke PolarizedThe Kazbek Z87+ safety glasses were designed for long days and demanding conditions. These safety glasses have an unmistakable lifestyle shape, available polarized lenses and an anti scratch coating. The Kazbeks frame is constructed of a nylon composite material that can be tied into a knot. And while we dont recommend tying yours into a knot, the rugged flexibility of the frame means you get a comfortable, yet equally durable, pair of safety glasses