Serengeti Positano 8371 Sunglasses combine a lightweight nylon frame with ultra-light mineral photochromic lenses for clear, contrast-enhanced vision on the road and in changing light. Key attributes: Dark tortoise | Nylon | Photochromic mineral lenses | Polarized lenses | Spectral Control technology | 100% UVA/UVB protection | Prescription lens compatible | Includes protective case and cleaning cloth | Modified square shape | Thin, lightweight frame | Dimensions & fit: Lens width: 56 mm | Bridge: 16 mm | Temple: 140 mm | Large fit | Base curve 6 | Composition & care: Frame: Nylon | Lens: Mineral glass | Wipe lenses with a microfiber cloth and lens-safe cleaner; store in the included case; avoid exposure to extreme heat or abrasive chemicals.