These are rated UV400 lenses. These flip ups fit onto aviator shape prescription glasses. Please note that these flip ups are pretty big and really fit best onto bigger size aviator frame glasses.
Aviator Flip Up Size
One single lens measures 60mm width x 55mm height
Total width across measures 138mm width by 55mm height
Your glasses need to be the same size or slightly smaller than the above specifications for the clip-on to fit properly.