Replaced the old CR-39 lenses in my Watsons. The black polarized lenses are noticeably darker, but stand up to bright sunshine better. Note: getting the old lenses out and new ones in is tricky as they fit VERY tightly. Hit that **** with a hairdryer for 2 - 3 minutes and work the old lenses out firmly, but carefully. Use the hairdryer again on the frame and new lenses and work them in. Worth the effort.