What are they? That's a good question. They were touted as climbing "skins," but they didn't work so well. I bought my first pair over 15 years ago because I didn't want to spend money on mohair. Mohair works much better than slick siped plastic.
I also found these:
What are they? Another good question. They are first generation heel risers to make skinning uphill a bit easier. Before climbing bars were integrated into bindings, we strapped sawed off PVC pipe on our leather boots to serve that purpose. The purple ones pictured above are the manufactured kind. They dangled around your ankles when you skied and skinned. And when you hit an incline, you strapped them under your foot. They worked about 25 percent of the time.
Evolution of backcountry ski gear in the last 15 years is impressive. In this time period, I have gone from three pins and leather to Chouinard cables to various telemark bindings (Rivas, Superloops, Hammerheads) to Dynafits and beyond :).
Fifteen years ago, the gear choice for hardcore ski mountaineers was severely limited -- practically non-existent. Descents of high mountain peaks with a free heel was tantamount to suicide. Although I'm sure there were some who attempted and succeeded on this kind of gear, most of the hardcore descents were probably being done on full alpine gear. For example, Johnstone and M. Newcomb's first descent of the Hossack MacGowan couloir on the Grand Teton was done on full alpine gear. That meant that they had to carry at least 20, and probably close to 30, pounds of skis and boots on their back! That doesn't include their other mountaineering gear. Any person capable of that deserves a lot of respect.
Today, backcountry gear has evolved to a point where it is essentially ski mountaineering gear, and very useful. Anyone can have a fully capable ski mountaineering setup that weighs 10 pounds, or even less. You can skin on this gear and climb on this gear, options some of the early ski mountaineering pioneers never had. This gear with the right pilot can handle the toughest of ski lines. With these huge advancements in gear, it stands to reason that today in 2011, much more is possible.