One correction about the writeup above... Vipers are blue, the La Sportiva Cobra is orange. The main difference between the two slippers is that the Vipers have no midsole, it's just rubber on the bottom there. The Cobra has a minor midsole in it, a plastic sheet in between the leather on the inside of the shoe and the rubber on the outside. This has the effect of stiffening the shoe and aiding in climbing on small edges and the like. And yes, the whole comment about if you manage to get your feet in them, they're the right size is completely true.