Tipping the scales at a feathery 18 ounces, the Outdoor Research Helium Bivy is ideal for moving fast through alpine terrain and wilderness expanses without excess weight slowing you down. However, don’t let its minimalist design fool you into thinking it’s lacking weatherproof performance or functional features. The Helium Bivy offers total waterproofing and maximum breathability with its Pertex Shield+ 2. 5-layer membrane, TPU floor lamination, and fully taped construction. Ultimately, this means you’ll stay pleasantly dry when you’re camping out in widely variable conditions, all without soaking in a sauna of built-up perspiration during humid summer months. The Helium features a clamshell design that promotes a restful night’s sleep with a Delrin Single-Pole system acting as a stabilizing structure for the bivy itself. The hood unzips during pleasant weather for extra ventilation and impressive stargazing potential. No-See-Um mesh lining keeps biting insects from eating you alive when you’re sleeping with the hood unzipped. Other key features include dedicated straps for attaching your sleeping pad, an internal mesh pocket, and stake-down points for securing this bivy in nasty weather.