The MSR E-Bivy is an ultra-light emergency bivy sack built to take up minimal space and weight. Weighing in at just over a ? lb, the E-Bivy takes up as much space as a can of soda. A fully waterproof bottom sheet is seam-sealed to a water-resistant and breathable top layer to allow for a comfortable enough night?s rest. This bivy works great for fast-and-light alpine climbing or as a backup emergency shelter.