Just the right amount of stretch. Much exertion and you'll get the standard garbage-bag effect, but it cuts through the wind and is a suuuuper lightweight addition for that extra warmth and wind protection. No reason not to bring it! The good and minimalist thumb straps are great additions - although the thumb straps are attached awkwardly to the inside of the seam, making the hem sit inside-out when using them. Still, 5 stars, and I love the bright color.