This weather-resistant little wonder has been on our list of essentials for nearly a decade. Perfectly minimal, the Houdini can be stuffed and put into a running short pocket, clipped to a harness or become a permanent fixture in a pack or carry-on. 100% nylon ripstop fabric blocks wind and a DWR (durable water repellent) coating protects against light precipitation. Slim fit accommodates baselayers and light midlayers. It's the emergency layer you don't know is there, until it's not.