The Helium Bivy used to be the best-selling, award-winning, lightest shelter offered by Outdoor Research - until we outshone it with this: The newly renovated Helium Bivy is significantly lighter than its previous version, the Helium Bivy is ideal for multiday minimalists who are looking to trade weight for speed, agility, and performance. Thru-hikers and bikepackers love the new Helium for its refined footprint and reduced weight, and trust it for its feathery waterproof and breathable Pertex Shield+ fabric that doesn't compromise on durability. A no-nonsense clamshell opening is sure to handle seasons of adventuring to come.Features Water-Resistant Breathable Abrasion- Resistant Durable Hypalon Instep Strap Reinforced Boot Lace Hooks Hook/Loop Front Closure Buckle Top Closure Elastic Bottom edge Specs Fabric: 100% nylon 420D packcloth leg panel100% nylon packcloth foot panel Weight: 6.3oz / 179g Avg. Weight for size M