While Assos has a multitude of seemingly complicated shoe coverings to choose from, these are easy to explain. They're the direct descendant of Assos' legendary airBlock bootie. The Assos winterBootie_S7 is aimed at the same temperature range and does everything the now-discontinued airBlock did, only better. To start, Assos employed the strataGon fabric for its enhanced waterproofing and breathability. It handles nasty weather better than airBlock, and ultimately, it leaves your foot more comfortable over a long duration. This new fabric's success hinges on Assos' new flexible membrane. Incredibly, the membrane closes down its microscopic pores when cold and opens them up when warm. Not only is the material more waterproof on its own, but thanks to the new panel design, it's increasingly difficult for water to seep in through the seams. There's a large panel that covers up to the ankle without seams, effectively shielding the entire forward portion of the foot with one seamless layer. Two smaller side panels run up from the heel alongside the ankles. The winterBootie is designed to fit snug around your shoe. While it might require a bit more effort to pull them on, they seal perfectly around your shoe once in place. The toes, cleat areas, and heels have been reinforced with an external layer of durable nylon swatches. The zipper is waterproof with a locking lever and a reflective stripe running the length of the zipper. The Assos winterBootie_S7 is part of Assos' climaRange 6. Assos calls this Winter, and defines its effective protection range being between 32-46 degrees Fahrenheit (0-8 degrees Celsius). The winterBootie is available in the colors Black and White and in Size 0 (35-38), Size I (38-42), and Size II (43-46).