These are fantastic sunglasses. The SR-91 lenses are crystal clear, and the polarization is excellent. These are great glasses when polarization is a must (flyfishing, being on the water or snow, or driving on wet roads).
I own the Hard Kore and also the Kore, and I find myself wearing the Hard Kore more often. The Kore are also great sunglasses, but the lens is bigger. While the bigger lens does a slightly better job of blocking light reflecting from below, they also have less air circulation, and are more prone to fog up. The Hard Kore, OTOH, allows a little better air flow, yet still provides excellent coverage. But by no means is the Hard Kore a small or narrow lens; actually, it's closer to the size of other "normal" shades. As should be evident by the picture, these shades do a great job of blocking lateral light, yet they are much lighter than they appear. Of my (too many) sunglasses, these are hands-down my favorites.