Our 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. 14% 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.