The best way to determine what size frame you need is to check the inside arms on your current frames. On the side arm (temple arm) you will find three numbers (for example: 51-17-135). The first is the lens width, the second is the bridge width, and the third is the temple length. All measurements are in millimeters. Apex Lenses are designed, tested and manufactured in the USA. We have unrivaled clarity, protection, and longevity than the other guys. We use only the highest quality materials and precision to keep your sunglasses at peak performance. Our lenses are 1.5mm thick, which are nearly identical to your original pair. With the added polarization, anti-reflective coating, and high-grade polycarbonate, our lenses ensure the highest optical quality. We stand behind our products and offer a 30-day warranty from the purchase date. If you are unhappy for whatever reason, we will refund your purchase for the full amount.