The Outdoor Research Aurora Bivy Sack provides lightweight, waterproof performance. Waterproof/breathable 3-layer Gore-Tex® Respiration Positive™ fabric and durable Hydroseal® coated waterproof nylon floor, combined with fully taped seams protects you and your sleeping bag from the elements while adding comfort. No-see-um netting at bivy opening to keep out the bugs. The end-opening zipper with wide storm flap adds ventilation and weather protection. When moving fast and light is the goal, the OR Aurora Bivy Sack delivers sold performance.