Smith glasses are awesome! My previous pair, the first interchangeable lens, lasted me 10 years and counting. I had to mend the screw hinges, but the rugged plastic frame persevered. I put 10,000 miles on my cross bike with those frames. The interchangeable lens really help with changing light conditions on a ride. The old yellow lens worked great for night biking.
I decided to upgrade to the Thresholds and love these even more! The polarized lens help with snow and water glare and the crispness retained is wonderful. I lost my first pair after 6 months and I am buying another pair. To the lucky duck that found my Smiths in Chicago, "Enjoy them!"