Extra skinny rectangle shape with polarized lenses. Polarized lenses are lighter weight on your glass frame and the polarized lenses eliminate glare. For the extra skinny rectangle shape to fit your glasses, your glasses need to be a very narrow rectangular shape with your frame rim measuring less than 3mm's thick. Measure one lens of your glasses carefully to the outside rim of your glasses width x height. We have many different sizes available and only one will fit your glasses, so it is very important to measure your glasses correctly. The extra skinny rectangle shape needs to be nearly the same shape as your glasses and the size clip-on sunglass needs to be the same as the measurement of your glasses or the next size bigger. All of our sunglasses and clip-on's are rated UV400 protection which is up to 100 percent protection. We include a microfiber pouch to store clean your lenses.