If you’re looking for a new waterproof jacket, chances are that you’ve heard of Gore-Tex. First introduced in 1978, it has long been the standard for waterproof/breathable garments. W.L. Gore does not itself manufacture garments; it lets approved companies use the Gore-Tex membrane in their own outerwear. The Gore-Tex membrane has approximately nine billion small pores per square inch, each many times smaller than a water droplet. The idea is fairly simple: the rain and snow consists of water droplets too large to penetrate the membrane, and sweat vapor is small enough so that it can escape through those small pores. And presto! You’ve got a waterproof/breathable fabric! Of course, Gore-Tex is not the only waterproof/breathable fabric on the market; there are many others, but they generally operate on the same principle as Gore-Tex: pores that are too small for water to get in, but big enough for sweat vapor to get out. There are several different versions of Gore-Tex, in its newest generation: Gore-Tex Performance shell, Pro Shell, PacLite shell, and Softshell. The Performance shell is the basic, standard version; it’s not too heavy, not too light, suitable for a wide variety of conditions. The Pro Shell is optimized for extreme conditions, such as mountaineering, where waterproofing, breathability, and durability are of paramount importance. The PacLite shell fabric is less durable than standard Gore-Tex, but it’s great for when space and weight are critical; it’s lightweight, and packable. Finally, Gore-Tex Softshell is a fabric that is designed to be warmer, and more breathable, than typical hardshells, while retaining superior waterproof integrity. All Gore-Tex garments come with the “Guaranteed to Keep You Dry” promise; if any Gore-Tex jacket fails to keep the water and wind out, they will repair or replace it. I was able to take advantage of their guarantee at one point; they are true to their word, and the service was superb. It’s difficult to go wrong with Gore-Tex.