Skinny curved rectangle shape clip on sunglasses are available in polarized and non polarized lenses. Polarized lenses are lighter weight on your frame and polarized lenses reduce the most glare. Non polarized lenses make it easier to see your digital devices outside. For the skinny curved rectangle shape to fit your glasses, your glasses need to be a similar rectangular shape with your frame rim measuring less than 3mm's thick. The clip on needs to be nearly the same shape as your glasses and the clip on size needs to be the same as the measurement of your glasses or the next size bigger. To help with sizing, we have printable templates below for the skinny curved rectangle shape. All of our clip on sunglasses are rated UV400 protection. We include a microfiber pouch to store and clean your lenses.