1) The frame should be made of soft nylon rather than plastic to prevent the fitover sunglasses from clattering against prescription glasses and to provide flexibility if stepped on. 2) The temples need to be adjustable to allow customization for a secure and comfortable fit during extended wear. 3) An "undercarriage" is important to block light penetrating from below and diluting the sunglasses' effectiveness, so look for a return scoop on the bottom side.

1. TOP FIVE TIPS
BUYING A FITOVER SUNGLASS
Don’t buy a sunglass that has a plastic frame. It should be made of a soft
material like nylon which prevents the fitover from clattering against your
prescription glasses. Furthermore, plastic frames break very easily where as
a nylon frame will flex if it’s stepped on for example. Softer materials are
also more comfortable than hard, brittle plastic frames.
It’s important that the temples are adjustable. If the temples can’t be shaped
to a position that secures the fitover comfortably you may experience
discomfort and irritation during extended wear. Adjustable temples can be
customized to your preference at any time.
Up to 70% of light that reaches your eyes can be reflected of the ground.
Pavement, water, snow and sand are examples of surfaces that light will
bounce off. If your fitover sunglass doesn’t have an ‘undercarriage’, light will
penetrate from below and dilute the effectiveness of the sunglasses. Look
for a return scoop on the bottom side of the fitover. This ensures that your
eyes are completely isolated from unfiltered light.
Remember why you’re buying a fitover type sunglass. Don’t get misled by
choosing a brand that focuses on fancy colors or styles. Although those are
factors when choosing a fashion sunglass, they’re irrelevant when it comes
to fitover. Look for the features. The very best fitover glasses available
shouldn’t cost you more than $50. Paying more is unnecessary.
Most fitover sunglasses will eliminate 100% of harmful UV rays but if the
lenses aren’t polarized, annoying and sometimes blinding glare isn’t
stopped. You should always make sure that the glasses you’re buying are
100% polarized. Scratch resistance is another feature you should check for.
For more information about fitover style sunglasses, visit the Cocoons website at www.cocoonseyewear.com