Skins, Wax and Waxless Skis Skins are a synthetic replica of seal, snake and other natural skins in that they have microscopic scales, or hairs, that all point in one direction. When you use a temporary glue, on the bottom of your skis, you can mount the skins so that all of these little hairs point toward the back. Then, as you shuffle your feet (and skis) forward, the little hairs/scales grip the snow crystals and do a very good job of keeping you from sliding backwards downhill. Skins are amazingly effective at getting backcountry skiers uphill this way - they're almost as effective as snowshoes under the right conditions. At the top of the hill the skier takes the skins off, puts them away in his or her pack for a fast run back downhill. Then, if there's a need to go back uphill, again, the skier simply sticks the skins back onto the bottom of the skis - the temporary adhesive allows this to happen countless times each season until the glue wears off or becomes too dirty. It's then removed and a fresh coat reapplied. My personal preference is to use wax. Swix, and other companies, sell all varieties of wax for gliding and gripping different types of snow under varying temperature ranges. Although ski wax doesn't grip quite as well as skins it offers more speed and efficiency because once you get to the top of the hill there's nothing to take off - you simply glide back to the bottom without changing your wax or equipment. Waxing skis allows you to glide downhill from the top due to a slight bow or "camber" that's on the bottom side of the ski directly beneath the skier's foot/boot. When the skier places weight directly above this bowed area, or "wax pocket," the snow is gripped to either allow forward propulsion or to simply keep the skier from slipping backward downhill. Then, when the skier wants to glide forward there's little weight on the this wax pocket so not much gripping of the snow crystals take place. Although the entire length of the ski, on the bottom side, normally contains some kind of glide wax it's only the "wax pocket," beneath the skier's foot, that contains the wax necessary for gripping. Waxless skis are another alternative - they have small scales permanently molded into the bottom of each ski so you never have to apply wax or skins. Waxless skis, under certain conditions, can grip better than waxed skis but not nearly as well as skins. The problem with waxless skis is that they are generally slower on both level and downhill terrain because of the drag created by so many scales. Drag is an even bigger problem with skins for obvious reasons. In summary, wax, skins and waxless skis all have advantages when it comes to climbing steep hills and then gliding back down. My preference has always been wax. However, here in Colorado we have an advantage in that our snow is generally very "dry" with typical temperatures averaging below freezing. So, for most of the season a combination wax called "Blue Extra" works well for us - making for very effective climbing and really efficient gliding - generally keeping us a well ahead of those using waxless skis or skins... http://www.rogerwendell.com