The North Face Assault FutureLight Bivy is a waterproof and breathable lightweight bivy sack. The core of the bivy sack is the FutureLight membrane. This ultra-thin network of filaments features countless interconnected air holes, produced using nanospinning technology. The three-dimensional channels between the fibers allow the membrane to have more air inclusions compared to other membranes. This enables vapor to escape more easily while preventing water from entering from the outside. The technology also ensures good air exchange within the bivy sack. Perfect as a minimalist shelter for high-altitude climbing and expeditions, it has enough space for a sleeping bag, mountaineering boots, and a backpack inside.