The minimalist, four-season Black Diamond Twilight Bivy is built from water-resistant and breathable NanoShield fabric that keeps weight to an absolute minimum and packs down incredibly small, making it ideal for an emergency shelter or as a sleeping bag cover. Built with a zippered entry across the shoulders, it&&';;s easy to get into and use while sitting up. Frameless construction to minimize weight Proprietary NanoShield single-wall fabric Year-round performance