These designer prescription sunglasses are made to accommodate most prescription lenses.Made of Nylon.Serengeti Martino frames have a rectangle shape, which helps to balance rounded facial features. Frame shape is the most noticeable feature of a pair of glasses, followed by frame color and frame size. Top brands always have a large collection of rectangle frame shape glasses, as well as oval frame shape glasses.Serengeti Martino frames feature a fashionable full frame design, which is the largest component of designer eyeglasses brands collections. A rim all the way around the lenses, provides for maximum stability and durability.The frame has a saddle bridge without nosepads, a popular feature providing a sleek look.Designed for adults, this model has a Spring type hinge for greater comfort.2-year warranty. The warrantee by the manufacturer covers manufacturer's defects for the frame. As an online optical superstore, we can help to process a warrantee for you with the manufacturer, according to their return policy. See all Serengeti Serengeti Sunglasses Serengeti sunglasses can only be experienced one way – your way. For you, the journey is just as important as the destination. As the maker of the world’s finest driving sunglasses and the pioneer of photochromic technology, we understand and agree. The Serengeti Sunglasses experience is like none other. It’s the optimal balance of technology and craftsmanship found only in a signature pair of Serengeti eyewear. Serengeti Eyewear is known for its lenses. Serengeti has done what no other sunglasses brand has done - merged three leading technologies into one sunglasses lens: 1) Gradually-adjusting photochromic lenses, 2) natural color-enhancing Spectral Control® filters, and 3) Glare-crushing polarization.