Convert regular glasses into sunglasses for outdoor use, driving at night with polarized lens sunglasses clipFeatures: Transforms regular glasses into sunglasses. Reduce glare and eye strain,UV400 protection. Great for those who already have a pair of prescription glasses and do not want to spend more for a pair of prescription sunglasses! Easy to clip on glasses (not suitable for rimless glasses) Polarized lenses will be helpful for your safe driving or any other activities under the sun How to choose the right size: 1. With a ruler to measure the length