Peak Vision SD7 Crafted from lightweight but durable MagnesiumAluminum alloy, the SD7 frame couples the style and lightweight fit of a 3 piece rimless frame with the strength and durability of a full rimmed frame. SD7 features spring loaded temple hinges with fully adjustable silicon cushion temple ends and nose bridge pads. SD7 fits narrow to medium face shapes recommended for a hat size of approximately 7 18 7 58 . The NXT unbreakable lenses deliver perfect light management for both the sky and turf with amazing optical glass like clarity. This purchase comes with a microfiber lens care bag, a durable zippered hard case with clip, and a one year warranty. Distortion In addition to the challenges associated with single filter lens, most sunglass lenses today are injection molded polycarbonate plastic , a 40 year old manufacturing technology. This technology, while producing light weight and inexpensive lenses, also produces lenses with very poor optical clarity. The distortion created during injection molding is a visible and pervasive artifact of all current performance sunglass lenses and also interferes with the ability to visualize contours and estimate distances. The graphic to the right shows a pair of our competitor's sunglasses bottom and PeakVision Sports Performance Eyewear through an optics viewer that displays optical distortion as a rainbow effect. To address the distortion in injection molded polycarbonate lenses, PeakVision Sports utilizes a new material called NXT This new material provides clarity equivalent to optical glass at less than 40% of the weight, while offering scratch and shatter resistance far superior to traditional polycarbonate lenses. Additionally, NXT offers 100% UV400 protection! Dual Zone PeakVision Sports incorporates two different technologies into a noticeably unique and differentiated lens by integrating multiple color management filters into a sport lens made from a revolutionary new optical polymer. PeakVision Sports developed the patented Dual Zone filtration that utilizes different filters in two zones of a sunglass lens. In the upper zone, neutral density gray filtration eliminates overhead glare from the sun and enhances distance perception. Through precise color and light management technology, PeakVision Sport's upper gray zone gradually transitions into an amber lower zone which enhances a golfer's ability to read the topography of the green. For skiers, the upper gray zone transitions into a vermillion lower zone. . E