Outdoor Research Helium Bivy - The Helium Bivy is the lightest bivy that Outdoor Research makes. Made from the same material as their ultralight rain shell, the Helium II Jacket, this bivy weighs in at a feather light 18 ounces! It features a classic, no-nonsense clamshell design and is completely waterproof and breathable. The single shock-corded overhead Delrin pole gives you breathing room at the head while the removable no-see-um netting at opening keeps those peasky biting bugs at bay. Designed to fit thicker sleeping bags, the Helium also offers high volume in the feet area. The Outdoor Research Helium Bivy is your true minimalist bivy for fast and light solo expeditions.