nothing, but i'm on the water all year and the polarization cuts the glare on the water better than other shades I've used.
Gotcha. I'm very glare sensitive myself. And to be honest, the best glasses I've found in this regard (even better than my Ray Bans) is my pair of Harley Davidson daytime riding glasses. The only problem with them is that if I try to wear them when I'm not actually going down the road, they fog up due to the the padding under the lenses. But as far as knocking out glare, they are great.